plc

# PLC — Programmable Logic Controller Reference Quick-reference skill for PLC programming concepts, IEC 61131-3 languages, common instruction sets, and troubleshooting patterns. ## When to Use - Writing or reviewing ladder logic programs - Debugging PLC faults and I/O issues - Choosing between Structured Text, Function Block, or Ladder - Looking up IEC 61131-3 data types and timer/counter instructions - Setting up communication protocols (Modbus, EtherNet/IP, Profinet) ## Commands ### `intro` ```bash scripts/script.sh intro ``` Overview of PLC architecture — CPU, I/O modules, scan cycle, memory areas. ### `languages` ```bash scripts/script.sh languages ``` IEC 61131-3 programming languages: Ladder Diagram (LD), Structured Text (ST), Function Block Diagram (FBD), Instruction List (IL), Sequential Function Chart (SFC). ### `instructions` ```bash scripts/script.sh instructions ``` Common PLC instructions — contacts, coils, timers (TON/TOF/TP), counters (CTU/CTD), math, comparison, move. ### `datatypes` ```bash scripts/script.sh datatypes ``` IEC 61131-3 data types: BOOL, INT, DINT, REAL, STRING, TIME, arrays, structs. ### `faults` ```bash scripts/script.sh faults ``` Common PLC fault codes and troubleshooting steps — CPU faults, I/O faults, communication errors. ### `protocols` ```bash scripts/script.sh protocols ``` Industrial communication protocols — Modbus RTU/TCP, EtherNet/IP, Profinet, DeviceNet, OPC UA. ### `examples` ```bash scripts/script.sh examples ``` Example programs: motor start/stop, traffic light sequence, tank level control, conveyor interlock. ### `checklist` ```bash scripts/script.sh checklist ``` Pre-commissioning checklist — wiring, grounding, I/O mapping, safety circuit verification. ### `help` ```bash scripts/script.sh help ``` ### `version` ```bash scripts/script.sh version ``` ## Configuration | Variable | Description | |----------|-------------| | `PLC_DIR` | Data directory (default: ~/.plc/) | --- *Powered by BytesAgain | bytesagain.com | hello@bytesagain.com*