Programmable Logic Controllers - Dr. Jeff Jackson

1 3-1Dr. D. J. Jackson Lecture 3-1 Electrical & Computer EngineeringProgrammable Logic ControllersPLC Addressing and Basic InstructionsDr. D. J. Jackson Lecture 3-2 Electrical & Computer EngineeringBasic addressing For the Allen-Bradley PLCs and the simulator used, the input and output image areas (in addition to other data) are held in data files Each data file holds information such as Discrete input values Discrete output values Values associated with timers Values associated with counters Status information D. J. Jackson Lecture 3-3 Electrical & Computer EngineeringPLC data filesSimulator data filesAB PLC data filesDr. D. J. Jackson Lecture 3-4 Electrical & Computer EngineeringI/O memory mapping Basic AB PLC addressingX1 file typeI inputO outputS statusB binaryT- timerC-counterData file number(can be omitted for thebasic data files)Slot number (not used with the simulator)Word number: selectsa specific word ina data fileBit numberI/O located on the controller (embedded I/O) is slot added to the controller (expansion I/O) begins with slot D.

2 J. Jackson Lecture 3-5 Electrical & Computer EngineeringExample AddressingCPUM odule(slot 0)DigitalInputModule(slot 1)16 inputsDigitalOutputModule(slot 2)8 outputsWould occupy addresses I1 through I1 occupy addresses O0 through O0 D. J. Jackson Lecture 3-6 Electrical & Computer EngineeringBasic instructions Examine If Closed (XIC) Examine If Open (XIO) Output Energize (OTE) Output Latch (OTL) Output Unlatch (OTU) One-shot Rising (OSR)3-4Dr. D. J. Jackson Lecture 3-7 Electrical & Computer EngineeringExamine if closed (XIC) Alternate name: Normally open contact Use the XIC instruction in your ladder program to determine if a bit is on. When the instruction is executed, if the bit addressed is on (1), then the instruction is evaluated as TRUE.

3 When the instruction is executed, if the bit addressed is off (0), then the instruction is evaluated as symbolNormally open switch is openNormally open switch is closedDr. D. J. Jackson Lecture 3-8 Electrical & Computer EngineeringExamine if open (XIO) Alternate name: Normally closed contact Use the XIO instruction in your ladder program to determine if a bit is off. When the instruction is executed, if the bit addressed is on (1), then the instruction is evaluated as FALSE. When the instruction is executed, if the bit addressed is off (0), then the instruction is evaluated as symbolNormally open switch is openNormally open switch is closedAn XIO instruction inverts thestate of the bit it D. J.

4 Jackson Lecture 3-9 Electrical & Computer EngineeringOutput energize (OTE) Alternate name: coil This instruction is usually used in conjunction with XICor XIOor any other input instruction. If the Logic preceding the OTE instruction is true (1), the OTE instruction will be energizedInstruction symbolNot energizedEnergizedAn OTE instruction can only be the last instruction on a D. J. Jackson Lecture 3-10 Electrical & Computer EngineeringOutput latch (OTL) The OTL instruction is used only to turn a bit on and latch it onInstruction symbolLInitially notenergizedEnergizedLatched3-6Dr. D. J. Jackson Lecture 3-11 Electrical & Computer EngineeringOutput unlatch (OTU) The OTU instruction is used only to turn a bit off and latch it off OTL and OTU are generally used in pairsInstruction symbolUDr.

5 D. J. Jackson Lecture 3-12 Electrical & Computer EngineeringOne-shot rising (OSR) When the rung conditions preceding the OSRgo from false-to-true, the OSRinstruction goes true also but for only one scan The address on the OSRinstruction is a bit that is used to reflect the state of the input to the symbolOSRI:1/0 OSR outputOne PLC scan3-7Dr. D. J. Jackson Lecture 3-13 Electrical & Computer EngineeringBranches Branches can be inserted in ladder Logic programs to create parallel combinations of various ladder Logic elementsDr. D. J. Jackson Lecture 3-14 Electrical & Computer EngineeringMultiple Series/Parallel Branches Multiple series/parallel branches can be utilized with multiple inputs and also affecting multiple outputs in parallel3-8Dr.

6 D. J. Jackson Lecture 3-15 Electrical & Computer EngineeringPLC simulator usage Ladder Logic elements (instructions) can be dragged and dropped onto the ladder window to create a ladder Logic program The ladder Logic program is executed by going online, downloading the PLC program, and switching to run modeOFFLINE/ONLINE controlDownloadPLC run modeDr. D. J. Jackson Lecture 3-16 Electrical & Computer EngineeringProSim simulations The Logixpro simulator provides a set of built-in simulations The I/O simulation initially will be of most use since it provides access to simulated discrete inputs (switches) and outputs (lamps)3-9Dr. D. J. Jackson Lecture 3-17 Electrical & Computer EngineeringOther Prosim simulations Available simulators Door simulator Silo simulator Traffic simulator Batch simulator Dual Compressor simulator Bottle line simulator Four floor elevator simulator Most projects will involve designing ladder Logic programs to control these simulationsDr.

7 D. J. Jackson Lecture 3-18 Electrical & Computer EngineeringBatch simulator showing example I/O