Guides

Complete technical documentation for every GOPLC subsystem. Architecture diagrams, function signatures, parameter tables, and IEC 61131-3 Structured Text examples.

Getting Started

Start here — the complete manual and first-time walkthrough

GoPLC Complete Manual

The full reference manual — every subsystem, every config key, every ST function, every protocol. 36,000+ lines. Start here if you want the whole picture.

Getting Started

First-time walkthrough — install, create a project, write your first ST program, connect to a device, deploy. The shortest path from zero to a running PLC.

Platform

Core development tools, distributed execution, and visual programming

IDE & Runtime

Browser IDE, task scheduler, debugger with breakpoints + stepping, HMI builder, project files, protocol analyzer.

Visual Ladder Editor

Rung-based LD editor with XIC/XIO/OTE/OTL/OTU + TON/TOF/TP timers. Compile-validate-deploy-online chain. Click-to-force in live mode.

AI Assistant

Chat + autonomous control mode, 13 runtime tools, Claude/OpenAI/Ollama, code/HMI/flow generation, voice input.

Configuration

Every YAML config field documented: tasks, protocols, I/O mapping, DataLayer, AI, Node-RED, real-time, fleet, security.

System & Resilience

Hardware watchdog, crash-safe RETAIN with atomic writes and rolling backups, UPS monitoring (NUT/apcupsd), graceful shutdown chain.

Authentication & RBAC

Role-based access control with 4 roles, JWT authentication, audit trail, and 21 CFR Part 11 electronic signatures for regulated industries.

Alarm Management

ISA-18.2 alarm engine with 8 alarm types, state machine, shelving, deadband, delay, auto-ack, and HMI annunciator integration.

Edge Historian

Per-scan sampling with deadband, 3-tier decimation, log-all opt-in, InfluxDB and MQTT forwarders, burst capture on alarm.

Hot Standby & Failover

Active/standby redundancy with UDP heartbeat, full + incremental state sync, PID bumpless transfer, split-brain prevention.

Clustering

Boss/minion architecture, DataLayer pub/sub, fleet management, tested to 500 minions.

Node-RED

7 custom GoPLC nodes, Dashboard 2.0, AI-generated flows.

Protocol Analyzer & Store-and-Forward

Packet capture, PCAP export, offline buffering with automatic replay on reconnect.

REST API & Swagger

250+ endpoints — runtime control, variables, programs, tasks, protocols, licensing, diagnostics.

MCP Server

80 tools for AI assistants — Claude Code, Cursor, Windsurf. Programs, tasks, variables, HMI, debugger, fleet, protocol analyzer.

ST Language & Libraries

Built-in functions callable from Structured Text — data processing, integration, and fault tolerance

Timers, Counters & FBs

14+ fn

TON, TOF, TP, RTO, CTU, CTD, CTUD, SR, RS, R_TRIG, F_TRIG, PID, PIDE.

Math, String & Conversion

150+ fn

Trig, rounding, statistics, EMA/SMA, string ops, type conversions, bitwise, unit conversions.

JSON

22+ fn

Parse, build, query, modify JSON. Dot-path access, typed getters, JSONPath.

HTTP Client

16+ fn

GET/POST/PUT/DELETE from ST. Response maps, custom headers, webhooks.

File I/O

15+ fn

Read/write/append files, line-by-line processing, CSV logging. Sandboxed.

Database

18+ fn

SQLite, PostgreSQL, MySQL. Query, insert, transactions, schema management.

Data Structures

160+ fn

ARRAY, MAP, LIST, QUEUE, STACK, DEQUE, SET, HEAP/PQUEUE.

Resilience & Caching

35+ fn

Cache, circuit breaker, rate limiter, throttle, debounce, bulkhead, hysteresis.

Debug & Logging

36+ fn

Multi-target logging: file, SQLite, PostgreSQL, InfluxDB, syslog, console. Per-module levels.

Cryptography & Security

Hashing, HMAC, encryption, key derivation, certificates, TLS from Structured Text.

CSV & INI Parsing

Read/write CSV and INI config files from Structured Text.

Regular Expressions

Pattern matching, search, replace, capture groups in Structured Text.

SMTP Email

Send email alerts and notifications directly from Structured Text.

Entertainment & Show Control

Art-Net DMX, audio, video, lighting scenes, cue sequencing for show control.

Specialized Utilities

Scheduling, unit conversion, geofencing, alarm management, and other utility functions.

OSCAT Library

OSCAT-compatible function blocks — HVAC, building automation, date/time, signal processing.

Industrial Protocols

First-class client and server implementations for every major automation protocol

Modbus TCP

30 fn

Client + server, FC01-FC16, multi-device polling.

Modbus RTU

30 fn

Client + server, RS-485, bus scanning, RTU-over-TCP bridge.

EtherNet/IP

43 fn

Scanner + adapter, tag browsing, Allen-Bradley integration.

Siemens S7

38 fn

Client + server, DB/I/Q/M areas, S7-300/400/1200/1500.

OPC UA

36 fn

Client + server, node browsing, security policies.

MQTT

36 fn

Client + built-in broker, pub/sub, message queue, QoS.

Omron FINS

23 fn

Client + server, DM/CIO memory areas, CJ/NJ/NX series.

DNP3

25 fn

Master + outstation, BI/BO/AI/AO/counter, SCADA/utility.

IEC 104

27 fn

Client + server, SP/DP/float/scaled/counter, power grid.

BACnet

36 fn

Client + server, priority array, COV, WhoIs, HVAC/BMS.

SNMP

36 fn

Client + agent + trap receiver, OID helpers, datacenter monitoring.

DF1

16 fn

Client, SLC 500 / MicroLogix, N7/F8/B3 file addressing.

Sparkplug B

16 fn

Edge node, NBIRTH/NDATA lifecycle, Ignition integration.

SEL Relay

54 fn

Client + server + meter. Mirrored bits, SER, oscillography, COMTRADE, settings.

CAN Bus

32 fn

SocketCAN raw frames + CAN FD, J1939 PGN decoder, OBD-II passenger-car PIDs, DBC file decoder. vcan-friendly for bench testing.

NMEA & GPS

0 fn

GPS position, speed, heading, satellite info from NMEA serial streams.

InfluxDB

16 fn

Write + batch, line protocol, Grafana dashboards.

CNC, Laser & 3D Printing

Stream G-code to machines with real-time parsing, parameter modification, and multi-transport support

G-Code

41 fn

File I/O, line parser/modifier, machine connection, status, position, pause/resume/stop. xTool HTTP, GRBL serial, Marlin serial.

Motion Control

0 fn

PLCopen MC function blocks — axis lifecycle, homing, jog, absolute/relative moves, multi-axis coordination.

Hardware Interfaces

Connect microcontrollers and USB devices directly to your PLC logic

Direct GPIO

7 fn

Linux SBCs (Pi, Orange Pi, etc.)

Imperative pin access from ST — GPIO_READ/WRITE/TOGGLE/MODE + I2C_SCAN. No manifest, no address mapping. For prototyping, diagnostics, and one-off utilities.

Parallax P1

16 fn

Propeller 1 (P8X32A)

GPIO, SPI, UART, I2C, PWM, servo, frequency counter, pulse measurement, quadrature + step-dir encoder. 4960-byte Spin firmware with dedicated cogs.

Parallax P2

82 fn

Propeller 2 (Rev G)

44 binary protocol commands + 38 convenience functions. Smart pins, UART, I2C, SPI, ADC/DAC, PWM, servo, encoder, OLED, animated eyes.

Arduino

20 fn

Uno R4 WiFi

GPIO, 14-bit analog, PWM, DAC, I2C, servo, WiFi, BLE, LED matrix, HC-SR04.

Teensy

47 fn

Teensy 4.0

CAN bus, hardware PID, complementary PWM, NeoPixel, encoder, RTC, TRNG, SPI, UART.

Flipper Zero

31 fn

Flipper Zero

NFC, RFID (125kHz), Sub-GHz radio, infrared, iButton, GPIO.

RP2040-Zero

26 fn

Waveshare RP2040-Zero

GPIO, ADC, PWM, NeoPixel, I2C, SPI, UART, servo, OLED, distance, temp sensor. Rust firmware.

ESP32 HMI Dongle

ESP32-S3-LCD-1.47

WiFi status display + USB mass storage. mDNS auto-discovery, live scan times/faults/memory, OTA updates.

Phidgets

16 fn

Phidgets USB

Voltage, current, temperature, humidity, load cells, relays, motors.