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Home/Guides/Pi PLC programming/Node-RED as a soft PLC
GUIDE5 min readUpdated Jun 2026

Node-RED as a soft PLC

Flow-based logic, protocol bridging and dashboards on a Pi — not a PLC, but the glue that ties a smart line together.

SHORT ANSWER

Node-RED is a flow-based programming tool that's superb for integration: wiring sensors, protocols (Modbus, MQTT, OPC-UA) and dashboards together visually on a Pi. It isn't a deterministic PLC and shouldn't run safety or tight control loops, but it's often the fastest way to bridge brownfield gear to the cloud and build an operator dashboard.

Flow-based
visual wiring, low-code
Node-RED
MQTT/Modbus/OPC-UA
nodes available out of the box
Node-RED
Dashboards
built-in UI nodes
Node-RED

01What it's great at

Connectivity and visualization. Read a PLC over Modbus, transform the data, publish to MQTT, and render a live dashboard — in an afternoon, with no compiled code. For retrofit and IIoT gateways, Node-RED is frequently the whole job.

02What to keep off it

Tight control loops and anything safety-related. Node-RED runs on Node.js and the event loop is not deterministic. Use it for supervision and integration, and keep deterministic control on a runtime or MCU.

Common questions

The ones we're asked on every first call.

For monitoring, integration and dashboards, often yes. For deterministic or safety control, no — pair it with OpenPLC/CODESYS or certified gear for that part.

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