S7 Communication Suite

The Problem

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Siemens S7 PLCs are everywhere in industrial automation — but connecting them to Node-RED has always been a trade-off. Pure JavaScript libraries work without native compilation but lack advanced features. Native Snap7 bindings offer full protocol support but are harder to install. And during development, you often don’t have a real PLC available at all.

The Solution

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A Node-RED package for Siemens S7 communication that lets you choose your backend — pure JS, native Snap7, or a built-in simulator — without changing your flows. Written in TypeScript for type safety and reliability.

blanpa/node-red-contrib-s7-suite

node-red-contrib-s7-suite

TypeScript

1

0

Three Backends, One API

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Switch backends in the config node — your flows stay the same.

6 Nodes

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flowchart TB
    R["s7-read"]
    W["s7-write"]
    T["s7-trigger"]
    CFG["s7-config"]
    PLC["PLC Connection"]
    BR["s7-browse"]
    CTL["s7-control"]
    R --> CFG
    W --> CFG
    T --> CFG
    CFG --> PLC
    CFG --> BR
    CFG --> CTL

• s7-config — Manages PLC connections with backend selection and auto-reconnection
• s7-read — Read multiple PLC addresses in a single request
• s7-write — Write data to PLC memory with dynamic addressing
• s7-trigger — Polling with edge detection and deadband filtering
• s7-browse — Discover available data blocks with filtering
• s7-control — CPU control operations (start, stop, cold start)

Supported Controllers

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S7-200, S7-300, S7-400, S7-1200, S7-1500, and LOGO!

Address Formats

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Three addressing styles — use whichever you’re comfortable with:

• nodes7-style: DB1,REAL0
• IEC-style: DB1.DBD0
• Area-style: MW4, I0.1, QD8

Reliability

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• Request queuing (max 100 concurrent)
• Exponential backoff reconnection
• Edge detection for boolean values
• Deadband filtering to reduce noise

Quality

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• Written in TypeScript with strict type checking
• Jest test suite with 80% coverage threshold
• Docker support for containerized deployment