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 |