The following is a growing list of ladder logic PLC programming instruction definitions and examples.

Each instruction is hyper-linked to a brief description.

The intent is to supplement the help files already provided with Studio5000 programming and configuration software. While the help files do a good job of defining the instructions, seeing believes.

The following definitions and examples are specific to Allen Bradley’s Studio 5000 software; however the concepts detailed here can be applied across multiple software applications.

*Must Read : A Simple (But Complete) Guide : PLC** Ladder Logic Programming(Basics)*

*Must Read : A Simple (But Complete) Guide: What is PLCs |PLC Basics| PLC Application|Advantage*

PLC Instruction | Meaning |
---|---|

ABS | Absolute Value |

ADD | Add Instruction |

AFI | Always False Instruction |

AND | Bitwise And Instruction |

ACS | Arc Cosine |

ASN | Arc Sine |

ATN | Arc Tangent |

AVE | Average Instruction |

BRK | Break (See FOR as well) |

BSL | Bit Shift Left |

BSR | Bit Shift Right |

BTD | Bit Field Distribute |

CLR | Clear Instruction |

CMP | Compare Instruction |

COP | Copy Instruction |

COS | Cosine |

CPS | Copy Synchronous |

CPT | Compute |

CTD | Count down |

CTU | Count up |

DEG | Radians To Degrees |

DIV | Divide |

EQU | Equal To |

EVENT | Trigger Event Task |

FAL | File Arithmetic Logical |

FFL | FIFO Load |

FFU | FIFO Unload |

FLL | Fill File |

FOR | For Routine Instruction (See BRK as well) |

FRD | From BCD |

FSC | File Search & Compare |

GEQ | Greater Than Or Equal To |

GRT | Greater Than |

GSV | Get System Value |

IOT | Immediate Output |

JMP | Jump To Label (See LBL as well) |

JSR, | SBR, RET Jump To Subroutine, Subroutine, Return From Subroutine |

JXR | Jump To External Routine |

LBL | Label (See JMP as well) |

LEQ | Less Than Or Equal To |

LES | Less Than |

LFL | LIFO Load |

LFU | LIFO Unload |

LIM | Limit Test |

LN | Natural Log |

LOG | Log Base 10 |

MCR | Master Control Reset |

MEQ | Mask Equal |

MOD | Modulo |

MOV | Move |

MSG | Message |

MUL | Multiply |

MVM | Mask Move |

NEG | Negate |

NEQ | Not Equal To |

NOP | No Operation |

NOT | Bitwise NOT |

ONS | Oneshot |

OR | Bitwise Inclusive OR |

OSF | One Shot Falling |

OSR | One Shot Rising |

OTE | Output Energize |

OTL | Output Latch |

OTU | Output Unlatch |

RAD | Degrees To Radians |

RES | Reset |

RET | Return From Subroutine |

RTO | Retentive Timer |

SBR | Subroutine |

SIN | Sine |

SIZE | Size array |

SQI | Sequencer Input |

SQL | Sequencer Load |

SQO | Sequencer Output |

SQR | Square Root |

SRT | Sort File |

SSV | Set System Value |

STD | Standard Deviation |

SUB | Subtract |

SWPB | Swap Byte |

TAN | Tangent |

TND | Temporary End |

TOD | To BCD |

TOF | Timer Off Delay |

TON | Timer On Delay |

TRN | Truncate |

UID | User Interrupt Disable |

UIE | User Interrupt Enable |

XIC | Examine If Closed |

XIO | Examine If Open |

XOR | Bitwise Exclusive OR |

XPY | X To Power Of Y |