The Raspberry Pi PLC started as a question about how cheap an industrial controller can get. These seven posts cover ZPi Controller: a Raspberry Pi Zero 2 W, a 4-input/4-relay board, and .NET 9 with Blazor on top.

ZPi Controller live monitor page

Modbus TCP/RTU slave and master, a rule editor you edit in a browser, a full-screen HMI built by conversation - all of it landed in v1. What actually took the time was one port number, one hostname, and a full minute of boot.

Building a PLC on a Raspberry Pi

The controller itself and the screen operators use, in two parts. Rules are edited in a browser; the HMI is written by conversation.

Connecting it, tripping over it, fixing it

Wiring it to a PC, and the things that caught us in the field. The obvious-looking places took the longest.

The next version, and one finished screen

The roadmap written while closing v1, plus one screen actually built in ZView.

What the Raspberry Pi PLC series comes down to

What decides a low-cost controller was never the rule engine. Every feature landed inside v1; the delays came from port numbers, hostnames, and boot time - the parts that look self-evident.

  • Rules are edited in a browser, and the HMI screen is written by conversation
  • Anything handed to a non-engineer has to install in a single double-click
  • Port numbers, hostnames, and regex replacements are where the days go
  • Boot time and automatic WiFi recovery are not features, they are the first impression

A controller is judged less by what it can do than by whether it puts itself back together within thirty seconds of power-on.

Contact