Allen-Bradley PLC 5/40

PLC 5/40 Details

• The front face showing Status LEDs, Communication Ports, Keyswitch, Battery and EEPROM installation
• The LEDs are for (from the top) Battery status, Processor status, Force status and Channel 0 communication status
• Apart from that, Each port (1A,2A,1B,2B) having their own status LEDs
• The steady green shows healthy, Red for fault
• 1A  and 2A Channels are used for Serial data transfer to DCS on DH+ Network
• 2B used for Panelview/MMI on PC/Redundant I/Os
• 1B used for RIO communication
• Channel 0 is for RS 232/ RS 422 Communication with the PC
• Lithium battery is for retaining the program in Processor when it is Powered OFF.
• EEPROM is to provide memory backup when processor memory corrupted

PLC In Refinery

• Mainly Allen-Bradley make
• PLC 5 and SLC family
• PLC 5/40 Having CPU Level Redundancy
• PLC 5/40L, 5/60 And SLC Installation
• Controls Operation of the Compressors, Heaters, Filters, F&G, Analyzer Safe Guarding and Other package units

Processor Architecture

PLC System Architecture

• Input means Signals from Proximity switch, pressure switch, pressure transmitters etc.
• Output means I/P converter, relay etc.
• This Inputs and Outputs are connected to the Digital Input cards, The digital output cards, Digital Output cards, Analog Input cards, Analog Output cards installed in the Remote I/O Chassis
• The PLC having local Chassis and Remote I/O Chassis
• The Remote I/O chassis is connected with PLC thru Belden 9463 (blue Color)
• Why Remote Chassis are required?
• Remote I/O adaptor Card is required for the Communication with the Processor. It always  remains in the first slot of the Chassis
• The Power Supply card in the Chassis is required to supply power to the complete chassis
• The 110Vac power supply is required for Power Supply card
• There are two Local chassis containing Processor.
• One processor is in primary mode and the other is in secondary mode
• The processor is having node address which can set by switch settings on the card
• The primary processor is connected on the DH+ network
• The connection is made in the Station connector normally mounted near to the chassis
• The primary processor appears as node no “n” in the DH+ network and the secondary processor appears as “n+1” in the network
• The KF2 module is connected on the network
• KF2 Module Converts DH+ data into RS-232 Signals which is compatible with AB Integrator in DCS architecture
• The KF2 and AB Module are act as link between PLC and DCS  
• The Panel view is used for monitoring the data of the  process as well as controlling the operation
• It is connected to the 2B channel of the processor
• The baud rate used for communication is 57.6 K
• Programming Terminal for Viewing, Modifying and Configuring the PLC Programming

Signal Flow In PLC

• The Field Signals are connected with I/O cards in RIO chassis
• Processor taking data from RIO chassis thru Remote I/O link and stores in I/P image tables / memory
• The data is being updated on every scan of the PLC
• The data is processed in Processor according to the program written
• The result is transferred to the output cards in RIO Chassis.
• The Output will be in the terms of 4-20mA or Contacts.
• The Processor updates the data on every scan, The scan time is in terms of milliseconds (averagely 40 mS)
• The scan of the processor means processor doing input scan, then program scan, then output scan, service communication and housekeeping. The time taken for completing this activities once is call scan time

System Redundancy

• Redundant DH+ Network for communication with the DCS (A and B network for DCS)
• The BEM cards are installed for increasing the no. of communication channels available for networking.
• Redundant 1770-KF2 modules for communications with DCS
• Both the PLC executes Application program
• Primary processor controls the I/O, but Secondary can monitor only
• The Switch over between processor is doing by BCM and BEM card

Software

• The program can written in Ladder Logic, Sequence function charts or Structured text format
• We have used Ladder Logic
• The Programming package is RsLogix5 (Windows based) and 6200 series Software (DOS based)
• The Software package can load into PC / Laptop
• The PC requires KT card and the Laptop requires PCMK card
• If KT/PCMK not available, then Processor can communicate on COM port of PC/laptop Serially thru CH0 on processor
• The RsLinx software is also required for the Communication over the network and serially
• The PLC program is protected with 4 different level access passwords
• In our complex, there is no password for the Reading the program online

Diagnostics

• There are status LEDs on the processor face
• The first LED is battery status indicator, if it glows RED, then Either the battery is low or missing
•  If the Second LED is steady green, processor is healthy
• If it is flashing red, the program downloading is under progress or major fault, for steady red, hardware fault
• The force glows steady amber when any I/P or O/P are forced in the program
• If Comm LED flashing green, the Channel 0 communication is working
• Any of the channel status LED glowing steady green, then that channel is healthy
• If it glows flashing Green, bad communication
• When it is red, adaptor fault