Data is obtained via the OBD2 (On Board diagnostics Protocol) – which is specified in SAE J1962 standard.
One of the most important data to obtain is data from the ECU (Engine control unit) or sometime termed as ECM (Engine control module). Sometime it is also called EEMS (Electronic engine management system)
The OBD2 (or SAE J1962) standard provides a standard list of PIDs (parameter identification umbers) for manufacturers to provide if they want to. They can also add in proprietary PIDs. For list of PIDs, see here (https://en.wikipedia.org/wiki/OBD-II_PIDs)
The OBD2 Protocol
OBD stands for Onboard Built-in Diagnosis. It is a diagnosis system that is built into all modern cars (after 1996) which has a computer based application that monitors stuff like speed, mileage, fuel emission data etc. Apart from this it also measures some of the important vital parameters of an Engine. This complete system is called as an ECU (Engine Control Unit).
The OBD2 specification sets a standard hardware connector to allow extraction of data. It uses a 16 pin SAE J1962 connector. OBD2 specification requires this connector to be within 2 feet (0.61m) from the steering wheel)
This connector PIN is unique as it allows 5 different signalling protocols
SAE J1850 PWM
SAE J1850 VPW
ISO 9141-2
ISO 14230 KWP2000
ISO 15765 CAN – this is the famous CAN BUS – THIS IS THE MOST COMMONT SIGNAL USED TODAY
The OBD connector is meant to be used only by the service guy to monitor the health of your Car and provide diagnosis. Apart from this it is also controls the warning lights on your Cars dashboard.
The OBD port can found below the steering wheel of every car
For large equipment, such as those use for mining, the protocol used is the same.
CAN Bus
A CAN bus is a low level communication layer used within vehicles.
Not to be confused with OBD2, as CAN BUS is the lower layer. CAN bus is one of the 5 protocol used in OBD2 Vehicle diagnostic standard. Out of the 5, it is the most common used.
It was released in 1986 by SAE (Society of Automotive Engineer), but only started to be used widely in the 90s
ISO released their own (but compatible to previous) CAN standards. Now the most common used is ISO 15765-2
The CAN Protocol is only for data transmission, it does not specify the Connector PIN (Or data link layer in the OSI 7 layer model).
Most manufacturers provide a 9-pin D-sub male connector for it. This is not to be confused with the 16 PIN SAE J1962 connector which has CAN BUS, on 2 of its pin. The 16 pin connector is used for diagnostics data and is specified in the standard.
The 9 pin connector is also the standard connector used for serial port communication like MODBUS.
Caterpillar Equipment
Caterpillar is the largest Heavy Mining Mobile Equipment Manufacturer. It dominates almost 16% of market share in 2018. The next closest is Japanese Komatsu (12%)
Since caterpillar is a US company, it uses OBD-2 for all of it’s vehicles (from small to mining equipments)
Caterpillar has it’s own diagnostic software called CAT ET (Caterpillar Electronic Technician)
Latest version is: Caterpillar ET 2019C
The ET software connect to a Caterpillar machine by means of an Adapter. The latest adapter is called Caterpillar Adapter 3. The connecting point is a J1939 connector (See picture below).
The versions are as follows:
CAT Adapter 2 (Caterpillar 275-5120/5121)
CAT Adapter 3 (Caterpiller 317-7484/7485) – Latest version
A Caterpillar adapter will normally have the following cables
J1939/J1708 Cable (Connects the adapter to the truck)
USB Cable (Connects the adapter to a PC)
This side (above) connects to the truck. This can be done with 3 types of connector (below) cables
J1939 Female – For CAN Bus
J1939 Type1 – For CAN bus
J4 Pins (PN 457-6114) for Caterpillar Excavator
This side (above) allows provides a female connector cable which connects to the PC via USB (PN 370-4617)
OPC UA
OPC UA
- OPC UA Local Discovery is a service provided by OPC Foundation which lists all the OPC UA's on a Machine. It listen to Port 4840
- OPC UA Security has several message security modes: - 1: No Security. The messages are neighther signed or encrypted - 2: With Security. The messages are signed or but not encrypted - 3: With Security. The messages are signed and encrypted
So what does this mean? - The OPC UA specification allows all these type of communication. Yes, including 'no security'! - However, an OPC UA Server will determine which one is allowed. - When a client is connecting to an OPC Server, he has the option to request what level of security he wants to connect to. - If 'No security' is used, this means: - There is no encryiption - NO SSL CERTIFICATE IS NEEDED. The client does not need to show a cert - The Server will accept all clients (Will not verify the SSL Cert)
- When an SSL Cert is required, OPC UA requres that such a cert is validated. - A Thumbprint is a unique id that is calculated by hashing via SHA-1 the contents of the cert. It has 40 characters - Validation is based on Subject Name which should be in the form of 'DC=ComputerName,CN=ProgramName". DC is distinguished name, CN is Common Name
- A client will need to scan the OPC UA Server and determin which security policy it implements. OPC UA Security Policies http://opcfoundation.org/UA/SecurityPolicy#None http://opcfoundation.org/UA/SecurityPolicy#Basic128Rsa15 (Obsolete) http://opcfoundation.org/UA/SecurityPolicy#Basic256 (Obsolete) http://opcfoundation.org/UA/SecurityPolicy#Basic256Sha256 [B] http://opcfoundation.org/UA/SecurityPolicy#Aes128_Sha256_RsaOaep [A]
- OPC UA Also allows authentication, typically authenticated againt windows username and password.
- In OPCUA Tree, each item is called a NODE. A Node can be of the following types; these are NODE TYPES (OR Sometimes refer to as Node CLASS) - Object = 1, - AN OBJECT IS BRANCH (YOU CANNOT SUBSCRIBE TO IT) - Variable = 2, - A VARIABLE CAN BE SUBSCRIBED TO. IT CAN ALSO BE A BRANCH - Method = 4, - A METhOD CAN BE CALLED - ObjectType = 8, - VariableType = 16, - ReferenceType = 32, - DataType = 64, - View = 128,
- Each Node regardless of whatever types, will have attributes. The following attributes must exist in all node types: - NodeId - Uniquely identifies a Node in an OPC UA server and is used to address the Node in the OPC UA Services - in OPCUA the NodeId, is rather confusing, like OPC Classic, the NodeId is a string, However, in OPC UA, it first - Starts with a NameSpace Index - A value between 0-65535 (Ushort) - Normally Namespace is zero (meaning no namespace) - The actual ID, which can be of 4 types: - Numeric = 0 (Unsigned Integer UINT, ranging from 0 to 4Billion) - String = 1 - Guid = 2 (A specific guid) - Opaque = 3 (An Array of bytes) - Fully Qualified Name - Since this naming can be complicated, it is common to use a combined name which will look like the following: - ns=<namespaceIndex>;<identifiertype>=<identifier> - Identifier type can be: - i NUMERIC (UInteger) - s STRING (String) - g GUID (Guid) - b OPAQUE (ByteString) - Specfying the Fully Qualified Name seems to be the common practice for OPCUA Connectivity - - NodeClass - An enumeration identifying the NodeClass of a Node such as Object, Variable or Method - BrowseName - Identifies the Node when browsing the OPC UA server. It is not localized - DisplayName - ontains the Name of the Node that should be used to display the name in a user interface.
- Nodes may have some additional attributes - The Variable Node Type must have in addition the the values - Value - The actual value of the Variable. The data type of the value is specified by the DataType, ValueRank, and ArrayDimensions Attributes - DataType - DataTypes are represented as Nodes in the Address Space. This Attribute contains a NodeId of such a Node and thus defines the DataType of the Value Attribute - ValueRank - Identifies if the value is an array and when it is an array it allows specifying the dimensions of the array - AccessLevel - A bit mask indicating whether the current value of the Value Attribute is readable and writable as well as whether the history of the value is readable and changeable - Readable = 1, - Readable | Writable = 3 - UserAccessLevel - Contains the same information as the AccessLevel but takes user access rights into account - The Attributes have attribute IDs - 1 = NodeId - 2 = NodeClass - 3 = BrowseName (A non-localized, human readable name for the node) - 4 = DisplayName (A localized, human readable name for the node) - 5 = Description (A localized description for the node) - 6 = WriteMask (Indicates which attributes are writeable) - 7 = UserWriteMask (Indicates which attributes are writeable by the current user) - 8 = IsAbstact (Indicates that a type node may not be instantiated) - 9 = Symmetric (Indicates that forward and inverse references have the same meaning) - 10= InverseName (The browse name for an inverse reference) - 11= ContainsNoLoops (Indicates that following forward references within a view will not cause a loop) - 12= EventNotifier (Indicates that the node can be used to subscribe to events) - 13= Value (The value of a variable) ---------------------------------------------------------------------------- MOST IMPORTANT!!!!!! - 14= DataType (The node id of the data type for the variable value) - 15= ValueRank (The number of dimensions in the value) - 16= ArrayDimensions (The length for each dimension of an array value) - 17= AccessLevel (How a variable may be accessed) - 18= UserAccessLevel (How a variable may be accessed after taking the user's access rights into account) - 19= MinimumSamplingInterval (Specifies (in milliseconds) how fast the server can reasonably sample the value for changes) - 20= Historizing (Specifies whether the server is actively collecting historical data for the variable) - 21= Executable (Whether the method can be called) - 22= UserExecutable - 23= DataTypeDefinition (Provides the metadata and encoding information for custom DataTypes) - 24= Permissions (The permissions available for the node) - 25= UserPermissions (The subset of permissions available for the current user) - 26= RolePermissions (The permissions granted to roles)
Instrumented Protection Functions
IPF Study
IPF (Instrumented Protection Functions) are functions which comprises of
· One or more initiators
· A logic solver or an Instrumented Protection System. Some refer it to as PLC
· One or more final elements
With the purpose to prevent and mitigate hazardous situations
IPF Study is a study which consists of
1. SIL Classification (Proceed with all)
2. IPF Verification
3. IPF Implementation
4. IPF Review – Every 5 years
SIL Classification
· Most time consuming
· Classifying consequence of IPF failure upon demand (Dangerous Failure)
· Classifying consequence of IPF initiated without demand (Safe Failure/ Spurious Trip/ Nuisance Trip)
· Classifying demand rate. Demand rate is a scenario that causes demand for an IPF
· To assign SIL
· No calculation – just assign SIL. In verification will only be calculation
· SIL Requirements
o 0 no IPF required – In PPTSB 90% was SIL 0
o a1 – Pre-alarm is adequate
o a2 – Triggers a switch action (interlock from DCS) + pre-alarm. Can integrate with control function
o 1 – Triggers switch action + pre-alarm.
§ Final Element can be control valve if fail safe
o 2 – Trigger switch action + pre alarm
§ Final element can be control valve in 1oo2
§ Share initiator with control transmitter in 1oo2
o 3 – Trigger switch action + pre-alarm
§ Share initiator with control transmitter in 2oo3
o 4 – Shall be avoided, very low PFD, more economical to redesign
· PFD
o Sil 1 : 1/10
o Sil 2 : 1/100
o Sil 3: 1/1000
o Sil 4 : 1/10000
SIL Verification
· To verify the installation at site. Look for common installations. Audit like
· Calculate the PFD (Probability of Failure Upon Demand)
· To obtain as low as SIL requirement
· Is calculated by obtaining
· HWFT (Hardware fault tolerance)
· DCF(Diagnostic Coverage Factor)
· Safe Failure Fraction (SFF)
· Number of safe failures vs number of total failures
· Proof Test Coverage Factor
· How much unsafe failures one covers during testing
· Test and repair durations
· Mission Time
· The time between test intervals
· Mission – The mission is referred to the mission the IPF is taking during it’s operation
· The smaller the mission time, the lower the PFD
·
·
· 2 Layers of verification
· Architectural Constraint. Consists of the following :-
· Hardware Fault Tolerance (HWFT)
· Is the tolerable number of dangerous failures in the IPF
· For 2oo3, HWFT = 3-2 = 1.
· For 1oo3, HWFT = 3-1 = 2
· For 2oo2, HWFT = 2-2 = 0
· Safe Failure Fraction (SFF)
· Any hardware can be
· Working Normally
· Safe Failure
· Dangerous Failure (Already failed but not known)
· SFF is the ratio of safe failures to the total number of possible failures (Safe + Dangerous)
· Provided by manufacturer
· Type of Instruments
· Type A – All failure modes and effect known. Well documented.
· Type B – Complicated Instruments
SFF
HWFT
0
1
2
< 60%
SIL 1
SIL 2
SIL 3
60% - 90%
SIL 2
SIL 3
SIL 4
90% - 99%
SIL 3
SIL 4
SIL 4
> 99%
SIL 3
SIL 4
SIL 4
Type A Instrument Used
SFF
HWFT
0
1
2
< 60%
N/A
SIL 1
SIL 2
60% - 90%
SIL 1
SIL 2
SIL 3
90% - 99%
SIL 2
SIL 3
SIL 4
> 99%
SIL 3
SIL 4
SIL 4
Type B Instrument Used
Safety Integrity Levels (SIL)
· Safety Integrity Levels (SILs) are a safety-measurement standard defined by IEC in IEC61508 to quantify the chance of dangerous failures in electrical or electronic safety devices, that is, the probability of the device to fail in performing its Safety function.
· Four SIL levels are possible, with SIL4 being the most dependable and SIL1 being the least. Each are based on it’s corresponding PFD (Probability of Failure Upon Demand) – Which is the probability that an instrument will not respond to a demand. It usually works on frequency of demand
SIL
PFD
· 4
· 10-5 to 10-4
· 3
· 10-4 to 10-3
· 2
· 10-3 to 10-2
· 1
· 10-2 to 10-1
· TÜVs (Technischer Überwachungsverein) are German organizations that aim to protect humans and the environment against hazards coming from factories and mechanisms of all kinds. As an independent consultant, it examines monitoring-needy plants, motor vehicles, energy installations and devices. The many subsidiaries of the TÜVs can also appear as project developers for energy and traffic concepts, problem solutions in the area of environmental protection and certification bodies
Lightning and grounding
Lightning
Lightning is the transient passage of electrons between a cloud to
· Surface of earth, 50% of all lightning are cloud to surface
· Another cloud
· Air
There are also ground to cloud strikes but these are very rare
Lightning are formed when the atmosphere has high variation in pressure and temperature. Large particles will move down and small particlaes will move up. This causes and imbalance of charge as large particles are more negative. This creates a large potential difference which if large enough will cause all the negative charges to move down to the surface of the earth
Lightning causes damage to equipment in 3 different ways
· Direct lightning strike
· Carried lightning strike -lightning is carried by cable to an equipment
· Induced lightning strike – lightning induces electromagnetic field which creates surge currents. Magnetic fields can also induce
Interesting Facts on Lightning
· 99 % of strikes are of intensity exceeding 3000A, 50 % of strikes exceed intensity of 28000A and 1% of strikes exceed around 200,000A
· The duration of stroke are typically 100 microseconds while in exceptional cases it may exceed 1 second. The voltage present on a charged cell will be in the magnitude of 100MV
· The high current flashes start first from tall structures.
The damage lightning does are as follows
· For human , massive current flow causes disturbances in the human electrochemical system, nerve damage. The heat generated from lightning burning can turn sweat instantaneously to steam. These steam is known to blow of people’s boots, shoes and clothing.
· For Electronics, it can cause vaporization of PCBs, transistors and fuses due to the heat it generates when arcing through high resistance insulation.
· For other equipments, it can create sparks and if there is combustible gasses nearby, it will cause fire
It is experienced several times that lightning can travel in long distance electrical cables
Lightning Protection System
Lightning strikes equipment by the following
Direct strike – There is no way to minimize damage dobe by a direct strike. One can only divert the strike to somewhere else
Direct Energization – Lightning strikes on a cable/piping/tracks which there are equipment connected at it’s ends. Even when the lightning reaches the ground, it can still travel through underground cables and pipes.
Induced / Near Field Coupling(EMP) –Electric fields are developed adjacent of the strike path due to the tremendous negative potential. The electric field may rise up to 8000 V/m within a 1 mile distance. Voltage may not be enough to cause major arcing but enough to vaporize PCB, Transistor and fuses.
Ground Potential Raise – When lightning strikes on the ground, it causes a ground potential gradient. This will cause some small surges. Example : A 100MV lightning strike at 30,000A can cause a ground potential of Rise of 75000V
Lightning damages electronics/instruments by the following
Memory discharge – Data loss, software corruption
Degradation – Degradation of electronic components due to transient currents
Damage by heat – High current flowing can create heat
Although lightning is devastative, 95% of electronics fail due to degradation of equipment are not from lightning, but from transients currents, which occur momentarily from
Collapsing magnetic field in inductors
Charging and discharging of capacitors
The most important thing that needs to be done to avoid lightning strike is to ensure that all critical equipments potential rise together and no potential difference is created. Totally eliminating lightning is not possible. When there is a potential difference, this will cause arcing which is a source of ignition and extreme heat. It is important that all metallic equipments are connected together with the earthing grid
A lightning protection system is a system which protects a structure from lightning strikes either by safely conducting the strike to ground or preventing the structure from being struck.
The main components of a lightning protection systems are
Air termination / electrode / lightning rod
Down conducter – to conduct lightning for the air termination
Earthing / grounding system – to dissipate the charge to earth
Bonds and clamps – to connect all the systems together
Surge arrestors
The down conductor must be put around a building, distanced
10m apart for tall buildings (>20m)
20m apart for short buildings (<20m)
Grounding System
All plants have a single earthing grid buried inside the soil of the earth. In between these earthing grids, an electrode will be plunged to the ground. The earth electrode is a galvanized steel pipe. The rod’s are >9m
Surge Arrestors
A SPD (Surge protection device) or lightning arrestor is a device which limits the current going through the line by channeling the excessive current to ground. Lightning arrestors must be installed at every line
The most effective protection is combination of SPD (surge protection device) at both ends, together with a low impedance grounding system
SPD shall be before the barrier
Instrument – SPD – Cable – SPD – Barrier - DCS
SPD is not used in off shore since there is no lightning in off shore platform
Instrument Earth and Electrical Earth is connected by a High frequency choke
Lightning is a very high frequency voltage
The choke is actually a HF inductor which give low impedance at high frequency
This allows IE and PE to be equalized during lightning
The choke shall be protected by a 100v surge protector put in parallel with the choke.
The surge arrestor is normally a GDT type
At high voltage, it will give low impedance
During lightning, the surge arrestor will have low impedance and hence allows current to flow through it
This reduces the current flowing through the choke hence protecting it from damage
Types of SPD
GDT (Gas discharge Tube)
Has a gas which becomes highly conductive at high voltage
Diverts the charge to ground
Zener Diode (Most Commonly used for instrument)
Zener diodes allow current to flow in the opposite direction at larger than the zener voltage
When high voltage occurs during lightning, the zener diode (arranged upside down) will flow through to ground
Metal Oxide Varistor (MOV)
At high voltage, it has low resistance but at low voltage has high resistance
When high voltage occurs during lightning, the MOV will have low resistance and route all the current through it to ground
SPD Type
Advantages
Disadvantages
GDT
Can be used for AC
Zener
Provides hardest clamping
Cannot be used for AC
MOV
Can be Used for AC
Grounding / Earthing
Earthing is the conduction of fault electricity current to earth.
Earth is used because it is the most reliable low impedance path of the fault current
The purpose of equipment earthing is
In electrical circuits it is used as a current sink since it has the ability to absorb a high amount of current without changing it’s potential. Though this is rare
For electrical supply, it is used as a common neutral reference. The grounding is done at a distribution sub station. As a normal user, we will see this as neutral terminal in our 3 pin socket
For lightning protection i.e. to ensure safe route of lightning and transient current to ground so that it will not effect other equipments
For EM reduction i.e. to sink electrical noise in signal transmission cables (such as telephone, microphone and etc)
Every plant will have a plant earth ring. This will be one of the first things people will do during construction of a plant. The earth ring are made of conductors sized at 70mm2.
Instruments are connected to the plant earth ring via a earthing cable. The size of the earthing cable for instruments are recommended at 25mm2.
The earthing resistance of any earth electrode or ground rod is made up of:
Resistance of the (metal) electrode – This is usually neglected
Contact resistance between the electrode and the soil – This is usually neglected
Soil resistivity
The temperature effect on soil resistivity is negative but is negligible for temperatures above freezing point.
In the plant we also have an instrument earth
Instrument earth is used to quickly discharge noise from screen wire cables to the ground. The screen cable are usually grounded at the control room and should be left hanging on the field side
These noise are normally from electromagnetic coupling between wires. As wires are typically bundled close to each other, current flowing through them will create electromagnetic field. These electro magnetic field can cause current in other wires
It is a common practice to have instrument earth totally isolated from the electrical system earthing grid. This is because if there is stray currents in the earthing grid, this may induce interference current in the instrument signal
The earthing system for instrument earth shall be as clean as possible. Therefore, it is important to put the instrument earth as far as possible from other earthing points. >5m should be okay
The earth resistance for instrument earth is very low typically <2 ohms. This is typically achieved by having an array of parallel electrodes planted. The electrodes will be connected by cable. Typically for instrument earth, there will be up to 10 earth electrodes
Should instrument and electrical earth be connected?
Latest technology has promoted EMC certified devices where they are more susceptive to signal noises. With the use of EMC certified devices, we do not need screen cables anymore
Normally in a plant, instrument and electrical earth are connected by an inductor and surge clamper.
The inductor is used to filter out high frequency noise from the earth grounding system
Electro Magnetic Interference
Electro magnetic Interference (EMI) is unwanted disturbance that affects electrical circuit due to electromagnetic conduction or electro magnetic radiation
Electromagnetic Compatibility (EMC)
Is a study branch in electrical engineering to try an ensure equipments are protected from EMI (electro magnetic interference)
The word EMC is commonly referred on a 2004 directive by the European parliament that:-
States the requirements of certified equipments do not emits electromagnetic signals that disturb other signals such as radio and television
States the requirements and governs the immunity of certified equipments to radio emissions
Manufacturers will usually seek EMC testing to ensure that they’re products are EMC certified
Wiring and Cabling
Wirings / Cables
Cable Glands
· Cable will be terminated by a cable gland before going into a junction box/equipment. The purpose of the cable gland is
· to grip the cable so that it hangs on to the equipment
· to void water ingress into the junction box
· To ensure hazardous are protection
The usual cable entry used is M20 type. The M’s range from M16 to M175 (smaller to larger cables). The complete M20 annotation is usually described as ‘M20x15’. 15 here means 15 mm length of the thread. M20 usually has a hexagon ring to ensure better gripping
Cable Gloves
After the cable gland, the cable will usually be covered by a cable glove. This is for cosmetics and also to avoid direct hit of rain on the cable gland.
Cable routes
Electrical and Instrument cables shall be 3m apart with exception of crossing. As long as the instrument cable is crossing perpendicularly with electrical cables, this shall have no effect. When crossing it should be at least >0.3m apart
Instrument cables should not be routed through severe EMI areas
If possible, cables should be routed though areas that are protected by lightning strikes
Cables should be routed near earthed steel structures and piping to reduce EMI
Transmission from field junction box to MDF must go underground in a multicore cable to prevent damage from fire or mechanical forces and also to prevent theft.
Cable Properties
· Cable thickness
· Cable thickness will determine the maximum cable carrying capacity.
· When one says cable thickness, it means the inner core NOT including the insulation.
· Cable thickness is usually measured in mm2 and will range between 0.005 to 100 mm2
· Sometimes cable thickness is measured in mm and this will range between 0.08 to 11 mm (you can calculate the area by using [PI*(D/2)^2]
· Field Instrument Signal wires
· use copper type wires which are usually around 1.13 mm
· The minimum cable diameter should be 1.13mm for single pair wires and 0.8mm for multicore wires (PTS)
· When specifying cable thickness, one will use standard. The most common standards used are
· American Wire Gauge (AWG)
· Standard Wire Gauge (SWG)
· Cable Capacitance
·
· Cable Insulation
· Cable insulation will determine the maximum voltage carrying capacity
· Screened or Unscreened
· Also called metal sheet. This is to remove noise and is made up of aluminum
· Metal sheet layer must be provided for small voltage signals to remove noise (Note that this wire must be grounded to instrument earth at the MDF). It is usually made of aluminum. TSometimes the metal screen will be also traced by a thin copper wire. This is to ensure continuity of the metal screen since usually, when the wires are bent, the aluminum sheath may tear apart. This wire is also called a drain wire
· Individual or overall screen
· Signal cables require screen while power cables do not
· The metal screen maybe available on every pair of cables. Even in a 10P-multicore cable, each pair will have a metal screen.
· Some multicore cable provide an single overall screen wire and do not have single wires on each pair
· Paired or Unpaired
· Some cables are paired while some aren’t.
· When they are paired, it is common to have individual screen for each pairs
· Inner layer insulating Material
· Typically polyethylene is used
· Outer layer insulating material
· Typically PVC is used because it is fire proof
· Underground Cable Protection
· Underground cabling must be provided with a special layer called AL/HDPE/PA (aluminium with high density polyethylene with polyamide (nylon) layer) to prevent moisture, chemical fumes or termite attacks. The AL (aluminum) layer also acts as a metal screen, hence no MS is required when AL/HDPE/PA is used
· Mechanical Protection
· Some cables will have an armour Layer
· It can either be steel wired armour or steel wire braiding
· To prevent mechanical forces, the use of steel wire armored or steel wire braiding is required (Note that this wire must be grounded to safety earth and the JB). Steel wire braiding is like a net style interface. This wire can also act as a metal screen. In this case the wire is grounded to the clean earth at the MDF. However some protective is installed at the cable gland of the JB so that the braided steels do not touch the gland since this gland is grounded to safety earth
· Fire Protection
· Fire resistant cables have a special layer before the SWA called ‘MICA’ a silica based material having high fire resistance.
· Fire retardant cables will have a high oxygen index. Oxygen index refers to how much oxygen is required to burn the cables. Normal cables will have oxygen index of 23% while fire retardant cables will have o2 index of 30%
· Thermocouple Cables
· If for thermocouple we require type K (Chromel Alumel) connections, which are red(+ve) and yellow(-ve) of color
Cable Construction Guide:-
· As a general guideline, instrument cables must have the following construction:-
· The conductor (Usually Copper Type)
· Insulator for conductor (Usually Poly Ethlyene)
· A Bedding Layer (To avoid direct contact of armour layer on screen) This layer provides insulation on the effect circulating ground currents (Since electrical earth is grounded in many places, current will flow in the ground wire due to ground potential difference)
· Cables shall be specified with low smoke and zero halogen. Halogen is very toxic to the body
PTS outlines a signal level class level from 1 to 5. Level 1 is for computer us signals, thermocouples and analyzers. Instrument 4-20mA signals are Level 2. Level 4 and 5 are for power cables.
KR2 Project instrument wire specs which are available in the market are of the following
· Cable Costs bought from vendor (who already marked up the price) in general are more or less the following
· 1P – RM40/m
· 10P – RM120/m
· Fibre Optics
Multi Mode
· Cheaper, more commonly used
· Has a larger diameter core
· 100 MBit/s for 2KM, 1000 MBit/s for 500m, 10GBit/s for 300m
· Multiple Data, Have 2 different wavelengths
Single Mode – Only 1 wavelength
· Cat 5 Cables
In the US the quality of cables to carry out signal is defined by CatX. Cat5 cable is currently the recognized cable for broad band transmission. Cat5e cable is the cable being recommended by IEEE and many equipment manufacturers. In the Europe they are rated in class, Class D being simlar to cat5 cables
CAT5 is an Ethernet cable standard defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA). CAT5 is the 5th generation of twisted pair Ethernet cabling and the most popular of all twisted pair cables in use today. It has 4 twisted pairs of copper wire terminated on an RJ45 connector. Cat-5e (CAT 5 enhanced) cabling supports frequencies up to 100 Mhz and speeds up to 1000 Mbps.
· Color Coding
The purpose of cable color coding is to know
·
Junction Box
· Cable entries shall be from the bottom. This is to prevent water ingress. If there is not enough space at the bottom, installation can be from the side. The cables however ned to be slanted to the bottom to allow water to flow downwards
· Ex junction boxes have a groove to allow heat to dissipate through. This will allow heat to go out of the junction box. CAUTION, it is wrong to tape the junction box as it will seal this groove. Experience has shown that when this groove is sealed, we may get melted termination blocks
·
Wired Signal transmission
Signal transmission in wires are exposed to the following 3 types of noise
· Magnetically induced noise.
· This is caused due to flux produced at the flowing current. When another wire is nearby, it will cause a flux cutting and induce voltage.
· Using a twisted pair wire will cancel out this induction
· Static noise.
· This is caused since two wires are close by, the wires create and imaginary capacitance between. The capacitance causes a build up of charge.
· By having a metal screen wire, this charge can be dissipated to clean earth (instrument earth)
· Common mode noise.
· This is the noise caused from the current created by different electrical grounding points
·
The electromagnetic spectrum are as follows:-
Wireless Transmission
Wireless transmission is performed by a medium called the electromagnetic spectrum. Currently only the radio and microwave frequencies are used for this communication
The electromagnetic spectrum are as follows:-
· 1 to 30 to 300Hz
· Extremely Low Radio Frequency (ELF) and Super low frequency (SLF)
· Used for Communication with submarines – This is a one way communication
· Waves are produces by mounting 2 large antennas apart
· Extremely slow communication, Few characters per minutes
· 300-3KHz – Ultra Low Radio Frequency (ULF) – Used for communication in mines
· 3 - 30KHz
· Very Low Radio Frequency (VLF)
· Can penetrate up to 40m deep under water
· Used for communication with satellites on the surface
· Used in electromagnetic geophysical surveys (detecting gold, minerals)
· 30 – 300KHz
· Low Radio frequency (LF)
· Used for navigation, radio clocks
· In some countries used for AM modulation
· 300 – 3000KHz
· Medium Radio Frequency (MF)
· Used for AM Broadcasting
· 3 - 30MHz
· High Radio Frequency (HF)
· Ionosphere can reflect these frequencies – Due to this HF has a very long distance. This phenomena is called skywave. Skywave is however effected by a lot of whether factors
· Used by amateur radios (private radios) since they would enjoy the long transmission
· 30 – 300MHz
· Very High Frequency (VHF)
· FM Radio transmission
· Previously used for black and white Television Broadcast. Could not be used for colour TV due to limited bandwidth
· 300MHz – 3GHz
· Ultra High Frequency (UHF)
· 450MHz is used for ATUR communication
· 900 – 1800MHz is used for Cellular Communication
· 900 Mhz band is used for Celcom and Maxis communication
· 1800 Mhz is used for adam.timecel and digi
· Wireless transmitters use 902 – 928 MHz Signal
· 470 – 800 MHz is used for color TV channels
· 2.4GHz Wifi Communication
· 2.45 GHz is used for microwave oven and blue tooth
· 3 – 30GHz
· Super High Frequency (SHF), popularly called the Microwave
· Used for WiMax
· Used for radar, as most objects reflect microwave signals
· Blue tooth use
As seen above, most signals are segregated by frequency. A recent technology, CDMA (Code Division Multiple Access) now allows signal to be segregated by code. CDMA is used for frequencies constructed from the band between
ISM (Industrial, scientific and medical) Band is a defined by ITU-R for the use of Industrial, Scientific and medical purposes which is free. All communication equipment must accept any interference from ISM equipment
Wireless signals are created by an Antenna which generates a radiating EM field
The government body which dictates frequency usage in Malaysia is the MCMC (Malaysian Communication and Multimedia Commission). We pay them yearly
About Handphones
· HP use a network called the cellular network. The cellular network is made out of cellular towers, normally known as cell sites. The most popular cellular network standard use is GSM(Global System for Mobile Communication)
· GSM operates in 2 frequency bands 900Mhz and 1800Mhz
· The first generation of HP, called 1G, uses analogues signals for communication.
· The second generation 2G, uses digital signals for communication. Voice signal is sent in a digital signal of around 10Kbits/s
· The third generation of mobile phones is 3G. This was enabled by packet switching technology which provides a higher bandwidth. Can go upto 1MBit/S
· The fourth generation of mobile phones is 4G. 4G is still conceptual, but the enabling technology would be the removal of all circuit switch communication into a fully IP based packet switched integrated system. It will also combine with Wifi and Wimax infrastructure. Can go up to 100Mbit/S
LOS issue can be as follows
· Size :- Obstruction which effects the signal must e larger than then the wave length
· Material :- If an obstruction is a good conductor, it will reflect the signal which is not good. However if the obstruction is a good insulator, the signal will pass thorugh. The degree to which a material is a good conductor or insulator also depends on the wavelength. The higher the wave length, the better the signal may pass through the object
The current most popular technology for wireless transmission is the Motorola canopy
The general frequency are as follows
· 0 – 4KHz : Telephone audio inside cables
· 25KHz – 1MHz : Broadband Internet
Comparison between 900Mhz and 2.4GHz
· 900Mhz more range
· 900 Mhz has more interference from pager and mobile communication
· 900 Mhz can reach without LOS
· 900 Mhz has lower power consumption
Range of wireless transmission is limited by the following factors
· The type of signal in use (i.e. the underlying technology), similarly to the fact that AM radio waves reach further than FM radio waves
· The transmitter's rated power
Wireless Transmitters
Wireless transmitter work in the ISM band of 902-928Mhz. Development is currently being done for 2.4GHz which has less interference and higher band width
Data rate is 4.8 kbps, 19.2 kbps and 76.8 kbps
Has CRC check to ensure data accuracy
Wiring cost saving of RM40 per meter
The waves sent are omni directional in comparison with Motorola canopy which is angles at +45 vertical and +30 horizontal
Range is about 600m but varies accordingly
Fire and Gas Detector
Fire and Gas (F&G) System
Consists of
· Manual fire call points
· Fire detectors
· Flammable gas detectors
· Toxic gas detectors
· Local Fire alarm panels
· F&G PLC
· Alarms
Alarms
· Loud speaker – For unit
· Optical Beacon
· Motor siren
· Strong sound
· For fire only
· Local Bell – Use in building
Local fire alarm panels
· Has a mimic panel to know where the fire originated
· Only for buildings, for plants, we rely on DCS.
· Purpose
· For fire brigade
· Because buildings are common alarm we need to know where fire is
· Types
· Addressable
· More diagnostics
· Chain loop topology. If 1 detector fails, the other detectors can till work
· Conventional
· One loop per room
· If 1 detector fails, all other detectors won’t work
Fire and Gas Voting
· A method to ensure robustness against failure
· Do IPF study for fire and gas – to be implemented
· Normally use 1oo2D
· Originally 1oo2, If 1 fault become 1oo1. Unlike safeguarding if 1 fault, fail safe
· For automatic, 2oo2
Fire Detection System
Type of fires are
· Flaming – From hydrocarbons
· Smoldering – Fire burning without flame
· Flash
For early detection one need to detect
· Smoke first
· Flame Second
· Heat last
Fire is detected by looking at
· Flame
· Smoke
· Heat
· Human visual
Type
Advantage
Disadvantage
When to use
Flame
Fast detection
Smoke
Early warning
Closed areas, for early warning
Heat
Hazard specific, less nuisance alarms, reliable
Cannot function test, damage replace, Slow response
When rapid fire spread is unlikely,
Person
Human Visual
· Manual Call Points
· In process area Installed at side of roads every 100 meters
· In offsite area installed at side of roads every 200 meters
Flame based fire detectors
Type
Principle
Advantage
Disadvantage
When to use
Infrared
Detect IR from flame flickering
Open fires
Cannot detect smouldering fires, Cannot detect H2 based fire,
Solar radiation interference
Preferred technology for hydrocarbon
Ultraviolet
Extremely Fast detection, open fires
Heavy smoke will foul the lens.
Welding, flare, black body interference.
UV-IR
Expensive
The best
IR multiple Freq
Visual CCTV
Smoke based fire detectors
· Smoke detectors provide the earliest warning for fires.
· From critical buildings, a concept called VESDA(Very early smoke detection apparatus) is utilized. In our plant, the system is called USSD (Ultra sensitive smoke detection). The concepts of USSD is
· Aspiration units are installed throughout the building. Installed normally on ceilings
· The smokes are sucked and brought to a central unit
· The central unit hosts an optical type smoke detector
Type
Principle
Advantage
Disadvantage
When to Use
Optical / Scattered light type
Smoke deflects beam of light
Good for smouldering fires,
Preferred choice, most common
Ionization
Smoke particles reduce current created from ion flow of radioactive materials
Sensitive to small smoke particles
Must be applied together with heat detectors
Only when ionization type cannot be used. Use in printing workshops, highly flammable places
Heat detector types
· Most commonly used inside plants since it’s hazard specific
Type
Principle
Advantages
Disadvantages
When to use
Fusible
Heat will melt a tube containing pressure
Cheapest
False alarms, easily
Continuous-line
Heat will cause insulators to melt and 2 conductors come in contact
Bimetallic
Heat causes metal to bend
Control is the art of keeping a measured variable at a desired level
How to determine where to put fire detectors?
· Best is use of F&G mapping software
· No standards, just based on principle (owner) study
·
· Installed at most likely place for leaks
· Mechanical seals
· High pressure Flanges
· If gas tend to go up, the detector should be place on top and vice versa
Gas Detection System
Flash point is the lowest temperature at which a liquid can form an ignitable mixture in air
Installed normally at
· Analyzer house
· Pit
· HVAC air intake for buildings in plant
Flammable gas detectors
Type
Principle
Advantages
Disadvantage
When to use
Electro Catalytic
Combustible gas oxidizes and produces heat
Robust, detects any combustible gasses, Cheaper
Catalyst can be poisoned,
Single point detection, fail-dangerous
Use when hydrogen detection is needed
Electro Chemical
Electrolysis of gas creates voltage
PPM Level, Good repeatability,
Cannot be used at high temperature and low humidity,
Must change electrolytes, Not fail safe, Gas specific (H2S, SO2,CO2,NO2, CL2)
Old technology, typically avoided, used mainly for toxic gas (see below)
Point type Infrared Gas Detector
Long service life, background gas does not effect service life, has diagnostic, fail safe
Cannot detect hydrogen
Preferred choice for HC plants.
LOS Infrared Gas detectors
Larger coverage
Expensive, high prone to nuisance alarms
Unit of measure is PPM Meter
Control is the art of keeping a measured variable at a desired level
The most common control algorithm used is the PID control
· H2S < 10 PPM, more than that is dangerous. 1000 PPM = dead
· HCL < 5 PPM
· Category 2 – Long Term (Vinyl Chloride, benzene, toluene)
·
Type
Principle
Advantages
Disadvantage
When to use
Electro Catalytic H2S gas detector
Combustible gas oxidizes and produces heat
Robust
For H2S detection
Electro Chemical
Electrolysis of gas creates voltage
PPM Level, stability, immune to environment change
Must change electrolytes, Not fail safe, Gas specific (H2S, SO2,CO2,NO2, CL2)
Preferred choice
Semiconductor
Instrument Intrinsic Safety
Instrument Safety
Intrinsically Safe is the state of a device, instrument or component that will not produce any spark or thermal effects under any conditions that are normal or abnormal that will ignite a specified gas mixture. Electrical and thermal energy limits are at levels incapable of causing ignition. It is common practice to use external barriers with intrinsically safe installations
Ingress Protection (IP) is derived from the IEC 60529 classification standard defining the state of an enclosure. IP has 3 digits, though 2 digit notation is the most commonly seen. The first digit is about solid contact, either 0(total contact, anything can get through) to 6 (not even dust can get through). Usually, 6 is used for process plants instruments since we do not want any dust to enter the electronic boards. The second digit is for protection against water ingress valued from 0 to 8. Usually 6 is used. In our plant, most of the instruments are IP65
IP First number - Protection against solid objects
0
No protection.
1
Protected against solid objects up to 50mm, e.g. accidental touch by hands.
2
Protected against solid objects up to 12mm, e.g. fingers.
3
Protected against solid objects over 2.5mm (tools and wires).
4
Protected against solid objects over 1mm (tools, wire, and small wires).
5
Protected against dust limited ingress (no harmful deposit).
6
Totally protected against dust.
IP Second number - Protection against liquids
0
No protection.
1
Protection against vertically falling drops of water e.g. condensation.
2
Protection against direct sprays of water up to 15o from the vertical.
3
Protected against direct sprays of water up to 60o from the vertical.
4
Protection against water sprayed from all directions o limited ingress permitted.
5
Protected against low pressure jets of water from all directions o limited ingress.
6
Protected against low pressure jets of water, e.g. for use on ship decks - limited ingress permitted.
7
Protected against the effect of immersion
IP Third number - Protection against mechanical impacts (commonly omitted)
0
No protection.
1
Protects against impact of 0.225 joule (e.g. 150g weight falling from 15cm height).
2
Protected against impact of 0.375 joule (e.g. 250g weight falling from 15cm height).
3
Protected against impact of 0.5 joule (e.g. 250g weight falling from 20cm height).
4
Protected against impact of 2.0 joule (e.g. 500g weight falling from 40cm height).
5
Protected
Fuel can ignite when the concentration of combustibles in air is between LEL(Lower Explosive Limit) and UEL(Upper Explosive Limit). This is because a correct Air to Fuel Ratio is required for a combustion.
An LEL meter detects the concentration of all combustible gases and translates it into percentage of an LEL limit. Typically, LEL meters are calibrated to Methane(CH4). Methane LEL limit is used as a reference for all other gasses. Most plants will set %LEL limit at 10% for hot works. This means that since methane LEL is 4.4%, if the gas detected is methane, the LEL limit will be 0.44%. From the view of an LEL meter, it will give 10%. 10% LEL is used as a safe level so that whatever the gas is, it is always safe to work since the LEL is still far away.
Equipment Protection
Area in a plant is usually divided into
· Classes or Zone
· Zone is used for Europe
· Zone 0 = Flammable material always present
· Zone 1 = Intermittent available and for long hours (>10 hours)
· Zone 2 = Not always available and for short durations only (<10 hours)
· Class is used in US
· Rosemount transmitters use
· Gas group
· Refers to a group of gas which has similar propertie as the group gas. The main property is the ignition energy
· Group I = Methane
· Group IIA = Propane
· Group IIB = Ethylene
· Group IIC = Hydrogen
· Temperature Classes
· Each gas has an auto ignition temperature
· An area can be classified from T1 and T6. T1 has the highest auto ignition temperature hence it is safest.
· An equipment can be certified as T1 to T6. This is the worst case temperature the equipment can get hot
Typically, for zone 1 it shall be 3m away from zone 0,
Ex is a certification chop for explosive protection equipment, i.e. equipments that protect explosion from happening such as JB and instrument enclosures. It is stated on the requirements from ATEX directive. In Europe, every Ex marked equipment shall have a CE mark
CE is also a mark like Ex. It was introduced by the European commission. With the CE sign, the product complies to the safety standards to be sold in Europe.
Protection types
· Ex ‘d’ = Flame proof – Not designed to be gas tight, energy is released through flame path, Large design to prevent explosion.
· Ex ‘o’ = oil immersion – used for transformers, Zone 1 and 2
· Ex ‘p’ = Pressurized – used for analyzers, Zone 1 and 2 – Equipment needs to be powered off if the enclosure is opened. This is why purging is ‘’not usually recommended
· Ex ‘q’ = Powder field – weighing machines, Zone 1 and 2
· Ex ‘ma’ = encapsulation – Zone 1 and 2
· Ex ‘d’ = Flame proof , explosion is confined within box– DC motors, Zone 1 and 2
· Ex ‘e’ = Increased safety, it is not possible for explosion to happen. The box is designed in such a way to prevent
· Connections oversized
· Terminations more robust
– Induction motors, instrument JB, Zone 1 and 2
· Ex ‘ia’ = instrinsic safety – if 1 component fails, IS can still retain - Zone 0,1,2
· Ex ‘ib’ = intrinsically safe, Zone 1 and 2 only
For zone 0
Matrikon Alarm MOC
Matrikon Alarm MOC / MOCCA / AMMOC
MOCCA stands for “Management of Change and Configuration Assistant”
Matrikon Alarm MOC has 3 different users
·Operator (User)
·A regular user
·Enforcer (Engineer)
·A super user, Can do what operator does
·Can enforce tag
·Can edit tag values
·Synonymous to a Process Safety Engineer
·Approver (Administrator)
·Can do what enforcer does
·Can start and stop channels
·Can Create and Edit Alarm Philosophy Matric
·Synonymous to System Administrator
The DCS Map File
·The purpose of the DCS Map file is to tell MOCCA how a DCS tag structure looks like and contains. It also determines which items come out in the TagBrowser Report
·The Sergregation between ALARM and GROUP is important to:-
·To know which is an Alarm and which is a Group from the Alarm Report
·An Incorrect DCS MAP File will cause the Channel Fail to start. It is therefore important to ensure the XML code is correct. E.g:-
·Comments must start with “<!--“ Comments and ends with “-->”
·Valid Values for TYPE
·String
·Real
·Integer
·Valid Values for EngType
·Ignore
·Value
·Range
·Valid values for Field Type
·None
·Priority
·TripPoint
·Unit
·Desc
·TagLevelAlarmStatus
·Priority Map Node Names Must be
·Low
·Medium
·High
·Emergency
·Other
·Discovered on 16/8/2011, not all cases where channel failed to start is due to DCS MAP FILE Failure… sometimes the sync service just becomes out dated. Resaving the settings in the ‘Manage Channels’ page would solve this. Discovered on 12/10/2011, resaving the DCS MAP file solved the problem
·For <TAGTYPE>,
·The Name attribute
·Indicates the type of tag
·Must match up with the Rules File (.rbf) TagType in the MOC rules builder
·Will be displayed in the AM MOC Tag type
·The Classification attribute
·Is used for the Alarm Point Type Distribution By Area
·This report answers the question of how many alarms are configured per tag (alarm/tag); which is then segregated by tag type
·The Value would normally be
·Analogue Input
·Analog Output
·Controller
·Other
·The <PARAMETER> child node
·lists down all the parameter to be scynchronized.
·If synchronizing from OPC, the Name attribute it must match the OPC Parameter Name (Such as PV,OP,PVHHLIM and etc) (Not the name in the rules builder). The parameter should be browsable from the Rules Builder
·The FieldType attribute determines the type of parameter. It must be either:-
·No Values (Default)
·Priority ç Alarm Priority, needs to synchronize
·TripPoint ç Alarm Set Point, needs to synchronize
·Unit ç Name of Unit
·Desc ç Appears in the Description Field
·[CHECKED ON 13/10/2011] The ‘DESC’ value is put in to Tell MOC that this is what needs to appear in the Desciption field in the web report. If there are more than 1 field having the ‘DESC’ value, the LAST ‘DESC’ field will be used in the the Description web report
·
·TagLevelAlarmStatusç Enabled State of Alarms
·E.g. if <Parameter Name=”AlmEnable” FieldType=”TagLevelAlarmStatus” TagLevelAlarmStatus = “1” />, this means that whenever The AlamEnable parameter is read as 1, it means this alarm is enables
·This is important for the disabled alarm report
·Note that this is for the TAG LEVEL. Meaning that if this parameter matches 1, the whole tag is considered inhibited (All Alarms Disabled in the tag). It is not for individual parameters within the tag being disabled
·I did an experiment where I had several parameters with TagLevelAlarmStatus. Only when all of them does not match the TagLevelAlarm Status (i.e. = 0 in this example), will the tag be registered as disabled or inhibited in the report. However, for the Tag to be enabled back (cleared from the disabled report), only > half the number of the alarmtaglevelstatus need to be activated.
·
·The EngType Field is a parameter setting to be used in the TagBrowser. It also effects the discrepancy report.
·Ignore – This is by Default (if nothing is specified). For this, the parameter is excluded from the discrepancy report
·Value – If this is specified, then the user can enter only a single value (in the Min field). If the value does not equal this value then it is considered a discrepancy
·Range – If this is specified, then the user can enter the Min and Max Eng value, as long as the actual value is between this, it is not considered a discrepancy
·
·Issus on Disabled Alarm
·Now what if an Alarm is disabled? By right it should not be shown as a discrepance if it is disabled. MOCCA takes this into account.
·By default MOCCA, assumes all alarms that has Severity value not in the priority map as disabled.
·As shown in the sample DCS map above, all alarms will be under an <Alarm> node and this node contains the severity.
·<ALARM Name= “PVHH>
·<ParamRef Parameter=”PVHH_LIM” />
·<ParamRef Parameter=”PVHH_SER” />
·</ALARM>
·By Default, If the priority value = ‘0’ then the alarm will be disabled.
·Additional disabling can be added by adding configured expressions e.g. Note that PVHHALMEN does not need to be configured in the ParamRef for this to work
·<ParamRef Parameter=”PVHHALMEN” /> ç Can be removed and still work
·</ALARM>
·In the MOCCA TAG Browser in OI, alarms which are enabled will be bolded
·
·
·The <PRIORITY> Child Node
·Is used to determine the Alarm Priorities available in the system.
·MOC has defined by default that alarms should be categorized as
·Low
·Medium
·High
·Emergency
·Other
·Hence, the priority map node must only be restricted to these values. A DCS Map file error will occur if the node values are not within these values
·This can be changed by (Have not researched this yet)
·The Value in the DCS map determines which value should map to that priority. This priority mapping value will be applied with parameters with FieldType=Priority
·IF there are more than 1 value which represents a particular priority. The node can be extended as follows:-
·<PriorityMap>
·<Low Value=”1”>
·<Medium Value=”2”>
·<Medium Value=”3”>
·<High Value=”4”>
·<EmergencyValue=”5”>
·</PriorityMap>
·Note that the value cannot be null or it will cause an error
·The priority map having emergency, high, medium, low is only important for the
·Priority Distribution By Alarm Condition Report
·Priority Distribution by Area Report
·
·
·
The VB SynchronizationScript
·After you edit a VB script, one does not need to restart synchronization. Tested on 12/10/2011, even if you edit the script while a MOC browse is occurring, the changes effect immediately
·The sync script must have the ProcessTag() subroutine and this must be executed
·In this script, the object Rawtag is exposed. This tag can be modified as follows
·Rawtag.DCSID – Get
·Rawtag.Name – Get, Set
·Rawtag.Qualifier – Get, Set
·Rawtag.Type – Get, Set
·Rawtag.Network – Get,Set
·Rawtag.Area – Get,Set
·Rawtag.Unit – Get,Set
·Rawtag.Parameters – Get,Set
·Rawtag.Parameters.Item(“PVHH_SER”) – Get, Set ç The ParameterName is called here
·The get items work for items not declared in the DCS Map
·The get item however does not work if the Parameter is not defined in the parameters section of the rules builder
·The rawtag Parameters.Item
·Note that the Sync Script is not persistant. The entire script (Outside and inside the processtag procedure is executed every cycle). Variables are not pass on the next execution. This is unlike AM
The VB MOC Structure Script
·The MOCCA structure script is a VBScript which invokes the procedure ProcessMOCStructure everytime it reaches a branch which satisfies the requirements outlined in both TAGDEFINITION and TAGTYPE (i.e a particular tagtype is identifier). THIS IS IMPORTANT!!!. The MOC Strcuture script is not executed at a branch that does not satisfy a tag definition
·This script is at every branch or movement of the OPC browsing while the Tag Update Synchronization is done.
·In this script, the object MOCStructure is exposed. This object holds
·MOCStructure
·TagCount ç Number of Tags in the Structure (As long as it fits the tag criteria defined in the Rules RBF file)
·TagList
·Item(i)
·ParameterCount çNumber of Parameters in the Tag
·TagType ç The type of tag as defined by the Rules (RBF)
·ParameterList
·Item(i)
·Name ç This is the Name of the Parameter, as it appears during MOC Browsing using MOC Rules Builder. In the Example Below the Item(x).Name (or Parameter Name) is “ALARM”. This NOTE : This Parameter Name is used in the Parameters Identification in the MOC rules builder
·ItemName ç This is the full OPC Item Path. It is the same path which is declared in the ODH Source Name Column. It can be used in VB scripts to make the OPC Call [TESTED ON 30/8/2011]. This is it’s true location
HarmonyNavigation/RootUnit/U-Batch and Chem Prep Harmony/U-Batch Mill Harmony/U31-Digesters/ILBP2:TYPE
(In this case the Parameter Name is TYPE. The “:” becomes a separater between Path and Item)
FI1001.Dog.Cat.PV
(In this case the Parameter Name is PV)
·
·Synchronize ç Set ad “true/false”. If false, item is not synchronized
For this reason, one can use a BLANK DCS MAP FILEand A BLANK MOC SYNCRONIZATION SCRIPT [TESTED ON 30/8/2011]
Blank DCS Map File:-
<?xml version="1.0"?>
<DCSMap>
</DCSMap>
Blank Sync Script:-
Private Sub ProcessTag()
End Sub
·
·NOTE, THIS WAS TESTED on 15/8/2011
·The ProcessMOCStructure script AND ALSO THE ProcessTag (Synchronization Script) execution is not persistent. If you declare a global variable (i.e. Dim X) outside the procedure, use it in the ProcessMOCStructure subroutine, it will not maintain the last value of X on the next execution.
·TESTED ON 12/10/2011 on the MOC Synchronization script: The code executes everything outside the procedure vs before going into the procedure. Therefore the object created need to be destroyed in the Process Tag Function (Set FSO=Nothing).
·The entire script is executed, on every MOC branch step. The top part, and also the script inside the ProcessMOCStructure. This is unlike AM where only the ProcessMessage() is executed for every step and the TOP part (normally used for object declaration) is executed at the start only once
·For A GLOBAL Variable, it needs to be declared outside the ProcessMOCStructure. If it is not declared outside, any assignments done to it inside the ProcessMOCStructure will not be passed to other subroutine..
·
·
Synchronization
·Regular Update
·Execute periodically. Executes also every time the service is started
·SQL server stores, all OPC item names (or paths). Performs the following query on SQL server, to get the item names
SELECT
AMTag.Name as TagName,
AMTag.TypeAS TagType,
AMOPCParameter.ItemName AS ItemID,
AMOPCParameter.Name AS ParameterName,
AMOPCParameter.PropertyCode,
AMTag.DCSID,
AMTag.Qualifier
FROM
AMTag innerjoin AMOPCParameter on
AMTag.ID =AMOPCParameter.TagID
WHERE
AMTag.DCSID = 7 AND
AMTag.ChannelName ='IM_Surrogate'
and HMTP = 0
·Quickly grabs all OPC values from the results of this query
·Does not browse the OPC tree structure
·(And therefore) Does not invoke MOC Structure Sctipe (ProcessMOCTag)
·Below is how the Synchronization Log File works when regular update is done
·Tag Update
·Execute Periodically as well
·Executes also every time the service is started
·Invokes the tag update synchronization script (Process tag), updates everything
·Invokes MOC Structure Sctipt
·Browses the OPC tree structure. This causes it to take longer!
Triggering the Synchronization
·Sometimes when restart service, both tag and regular update is performed if, scheduled start time is less than current time. If this does not work, play around with the manage channels. Change the time start to 1 minute later and save
·You can turn off the regular update and fast update cycle if you are only interested in the tag list update
·Regular Update Started
·Start of Tag list Update
·Tag List Update Completed
·Regular Update uses the data obtained from SQL to perform the update. The processing tag is done immediately (Invoking the Process Tag Script)
·Regular Update Completed
·Reasons Why Browsing Fails
·The start path is configured in rules builder (There is a bug here (26/07/2011).Removing in rules builder may fix it
·The tag definition in OPC item is not configured correctly (TAG DEFINITION IS CASE SENSITIVE!).
·Sometimes the regular update does not browse the tree. To fix, this you can play around with the options in the MOC Rules builder. There are 3 ticks (8 combinations). Changing this will have immediate effect on the program browsing (witnessed on 22072011)
Process Tag Synchronization scripts
·Installed in the process tag
Tag Deletion
·Tag is deleted using the MOCCA Excel Interface. Once a Tag is deleted, it should immediately dissappear from the plant hierarchy (no need to refresh netobjects or whatever)
·
·dsd
Plant Hierarchy
·Tag list update will rebuild the tree
·If a tag is already configured and the area need to change, the tag must be deleted first. Tag is deleted using the MOCCA Excel Interface
·Once the tag is deleted, when it is re-imported back, thenew object trees will be rebuilt.
·Note that the Net Object tree does not need to be deleted for this, only the tag
The rules builder is used to build an “rbf” file which contains the rules on what items to take and classify when MOCCA parses through an OPC server
·Note 1 2/2/2011 MOCCA 3.0.4 – The Set Start Path doesn’t’ work don’t bother to use it
·You can prevent the OPC server to go through an entire branch by right clicking => Exclude Branch
·You do not need to restart the synchronization service after the rules file has been changed.
The rules is structured into 3 parts
·Tag definition
·In an OPC structure there are many items (e.g. Alarms, Status, Tags, etc). This definition is used to identify which OPC structure is a tag.
·Rules can be built to determine a tag based on
·OPC Items
·Important! Take note that the OPC Item is not the parameter name or parameter item name, it is a hierarchy name based on the browse where each branch is separated by a ‘\’ . For this it is imperitave to take note that the Operator equals may not work for OPC item. One should use the endswith term instead.IMPORTANTTIP!!: To get a more precise rule. Use set the OPC Item rules as “Ends With \BAL” (For selecting only BAL parameter)
·The OPC Items need NOT BE DECLARED in the Parameters Tab of the Rules Builder for it to scan an OPC Item [TESTED ON 20/8/2011]
·OPC Branch
·OPC Properties
·Each Rule by default is an “AND” Operator. If one opens the RBF File, under <Tag Ident><Criteria> node, there is a possibility to change this from and “AND” to an “OR”. This change unfortunately does not work (as of 27/7/2011)
·The Path to Next…
·Is used to determine where is the tag. Typically it’s “..” means that the tag(name) is a parent to the node
·The Maintain Tag Types Hyperlink
·Tag types must be declared here. There are many tag types such as for a yokogawa system there are PVI, PID, PVO and etc.
·TagType and Parameters Definition
·The tagtype declares a rule of which of the tags belong to the defined tag type.
·The rules has lines, each line is and AND operator. If no rules are configured, here (i.e. no parameter or tag lines), no tags will be detected
·By Default, a tagtype “Default” is already created in a freshly opened rules file. This “Default” tagtype cannot be deleted Using the MOC Rules builder. It can however be deleted by directly deleting the tagtype node in the RBF File.
·NOTE!!! The “Default” Tag type will captue any tag even though nothing is declared in it’s parameter. By right one should not allow default tags to be synchronized
·To declare this part one can declare MOC Node Type by Parameter or By Tag
·By Parameter –
·If one selects this, one needs to define the parameters first on the parameter tab.
·IMPORTANT!! VERIFIED 22072011 The Name is actually the Parameter Name, which does NOT include the path.
·Table above shows the difference between parameter name and parameter item.
·The parameter tab is used to define the rules for which parameter is selected. Since we have selected the tag in tag definition, in the parameter tab, we need to select which parameters we need. An easy way is to take all parameter and define a very generic rule (such as ends with “”), this will results in the system browsing all tags including the tags we don’t want. (This does not effect the tag browser report as the tag browser report is based on what is configured in the DCS Map file). Picture below shoes this. All Parameters are highlighted green indicating all parameters have been selecting with this generic rule
·Each line in the rule is an OR parameter.
·Important! Take note that the OPC Item is not the parameter name or parameter item name, it is a hierarchy name based on the browse where each branch is separated by a ‘\’ . For this it is imperitave to take note that the Operator equals may not work for OPC item. One should use the endswith term instead. In the example above, the BAL parameter OPC Item is = Blablabla\Program\AC38_002\BAL. TIP: To get a more precise rule. Use set the OPC Item rules as “Ends With \BAL” (For selecting on BAL parameter)
·Once the parameter tab is done, the TagType tab is done next ( and yes, we do the second tab first ). Since we have selected the only parameters we want from the parameter tab, we can tell MOC that a certain tagtype must have these parameters. Each line in the parameter rules in an AND operator
·The TagType parameter works line-by-line, it first searches the first tagtype and how it is defined (as explained above, by specifies what parameters it have). If the tag type is taken, it accends down accordingly.
·Example is that a tag type PID, must have parameter P, I, and D. SO we specify “Ends with P”, “ends with I”, and “Ends With D” as tag type rules. If say MOC finds a A tag wouthout any P,I or D, in then checks the next tag types.
·By Tag
·Identification by Tag is basically based on the tag name (have not tried this yet)
·
·
Alarm MOC Excel Plugin
·You can install the Excel Plugin by downloading the plugin from OI
·You Can
Save and check the control drawing
Old Computers
Old Personal Computer Hardware SERVERS
Processors
The Elements
Number of Cores
How many physical CPU inside the processor
Number of Threads
How many virtual CPU working. This is shown in the Task Manager.
This terms of threads originated from Intel since they developed the ‘Hyper Threading Techonology’ which delivers two threads per physical core.
NOTE These are Hardware Threads, not software threads used in programming languages
CPU Speed
How fast it takes to execute instruction
Is important for single running applications
Not important for server as they have many applications. Even then, a single Server applications normally use parallel programming.
The Cache
Enables the CPU to retrieve recently used information quickly
In most cases, the more the cache, the fastar the CPU.
The Front Side bus (FSB)
Connection between CPU and Northbridge
Intel doesn’t use FSB, but uses DMI instead
Unit in GT/s
The System Memory
For server, it is good to use XEON due to:
It’s reliability, low heat and power consumption.
It is meant to run 24 hours.
Contrary to popular belief Xeon is not MORE powerful than conventional processor. It’s main advantage is reliability, e.g. It has some other improved reliability features such as ECC memory
Operating Systems
Windows
Windows Server 2008 R2 (July 2009)
Windows Server 2008 (February 2008)
Windows Server 2003 (April 2003)
Network Cards (NIC – Network Interface Card)
The first thing to check is the number of ports
Typically it’s either single or dual port
Meaning how many Ethernet cables can go in
The next thing to check is it’s connection
If it say PCIe only that means it is PCIe x1 and compatible with all PCIe slots (X1,X4,X8,X16)
Another thing to check is it’s bandwidth, they are:
Ethernet or 10BASE-X
Only supports up to 100Mbps or 1.25MBps
Old Technology
Fast Ethernet or 100BASE-X
Support up to 100Mbps or 12.5MBps
Old Technology
Gigabit Ethernet or 1 GbE
Supports up to 1000bps or 1Gbps = 125MBps
Backward compatible
Can use same CAT5 Cables and connect to 10/100 hardwares
However, it causes the new equipment to be slower
1GBe Ethernet has 5 Varieties in physical layer standards which are
Twisted-pair cabling (Cat‑5, Cat‑5e, Cat‑6, or Cat‑7)
100 meters
1000BASE‑TX
Twisted-pair cabling (Cat‑6, Cat‑7)
100 meters
TOE (TCP Offload Engine)
New Network cards especially the 1GbE types have TOE (TCP offload engine). What this does is that it has a processor which processes various TCP protocols such as the 3-way handshake which is supposedly to be done by the processor.
The purpose is to free up processor speed
Hard Disk
Interface
Hard disk commonly interfaces with the PC using a serial bus interface.
The most common interfaces:
SATA
Cheaper because it does not use a built in processor for controlling head position unlike SAS
SAS (Also known as SCSI)
Faster and more reliable
Some Hard disks have SED feature (Self Encrypting Device). This is for security purpose
Hot plug
A property of a hard disk which can plugged out when the server is running. This avoids server downtime when a hard disk change is required (due to faulty hard drive and etc). Hot plug hardwares cost more
RAID
Raid stands for (Redundant Array of Inexpensive Disks). The advantages of RAID
High Data Reliability and Availability
Ease of combining hard disk space
Improve Speed
Raid Controllers
When RAID is selected, a RAID controller needs to be installed. For dell, this is called the PERC (PowerEdge Raid Controller).
Types of RAID Controllers:
Software RAID Controller
Hardware RAID Controller
RAID Numbers:
0 (Stripping)
2 Hard disks mirrors each other not for redundancy.
It Doubles data transfer rate, theoretically, but in real life the gains are around 10%
Improves Performance
Minimum 2 Drives
1 (Mirroring)
2 Hard disks mirrors each other
Advantage
Highest Reliability
Disadvantage
Size is limited by the drive with smallest size
Minimum 2 Drives
2 (Bit Level Stripping with Hamming Code parity drives)
Improve data integrity and reliability
Obsolete
Minimum 3 Drives
3 (Byte Level Stripping with dedicated parity drive)
Hardly Used
Minimum 3 Drives
Same advantage
4 (Block Level Stripping)
Hardly Used
Minimum 3 Drives
5 (Block level stripping with distributed party)
Commonly Used
Advantages
Provides Redundancy up to one hard disk failure
Increase Disk Size to (DriveSize x (Number of Drives – 1))
Disadvantage
If more than 1 hard disk fail, ALL data are LOST
Minimum 3 Drives
6 (Block level stripping with double distributed parity)
Needs at least 4 drives
Tolerates up to two failures
Minimum 4 Drives
10 (Mirroring without parity and block level stripping)
Is a combination of RAID 1 and RAID 0
Works in Spans
Each span will mirror one another (Like Raid 1)
The upper span works like RAID 0
Advantage
Speed and Reliability Combined
Disadvantage
Less disk space compared to RAID 5
Motherboard / Chipset
DTE/DCE
DTE – Data Terminal Equipment, Ends a communication line (The processing node)
DCE – Data Communications Equipment, in the middle of communication line (The bridge)
PCI Slots (Peripheral Component Interconnect)
Conventional PCI
1991
33/66 MHz
6 types of slots
3.3V 32 Bit
5V 32bit
3.3V 64 Bit
5V 64 bit
Universal 32 bit
Universal 64 bit
32 bit PCI slots can be used in 64 bit slots
PCI-X
1999
66/133 Mhz
3.3V 64 Bit
Faster than Conventional PCI
Conventional PCI cards can be used on PCI-X slots
Supports Multi Drop
PCI Express / PCIe
2002
Formerly known as 3GIO
Have 4 types of slots
X1, X4, X8, X16
The smaller slots can fit in larger slots. That is why some hardware just specify itself as PCIe which means it is PCIe x1 and can fit in all slots
A typical motherboard will have these slots
Server Rack
The most common server rack is the 19” rack. It is specified in EIA , CEA and IEC standards
Typical rack servers are around 17 to 18”. The racks are mounted by a slide
Ethernet
Is a physical layer LAN technology which is defined in the IEEE standards. LAN is a network limited by geography
The standards
IEEE 802.3 (Also called Wired Ethernet or Simply referred to as Ethernet)
IEEE 802.11 (Commonly referred to as Wifi)
IEEE 802.16 (Commonly referred to as Wimax
RAM (Random Access Memory)
What is RAM?
RAM is a type of Computer Storage. The word random-access means that data can be read anytime without going through a sequential process.
However, today this has become a name only, modern DRAMs use burst mode reading which is sequential in nature but fast. SRAM however, still works in a RANDOM access way
RAM are Volatile
When power is lost, data is lost in the RAM.
Static (SRAM) vs Dynamic (DRAM)
SRAM is faster and more expensive. It is often used as cache memory for the CPU
Don’t need to know much about this other than when buying a CPU.
DRAM is slower and typically used as computer memory.
DRAM is the most common RAM Type.
DRAM Formats (these are just how the memory is designed)
SIMM (Single Inline Memory Module)
Old Technology
32Bit
RIMM (Rambus inline Memory Module)
Old Technology between SIMM and DIMM
DIMM (Dual Inline Memory Module)
MOST COMMON FORMAT
Typically around 4-5 Inches length
Replacement Technology for SIMM
64Bit
Twice more Pins than a SIMM, Faster than SIMM
The number of Pins in DIMM is determined by the specification type (e.g. DDR2, DDR3, SDRAM)