PIC Micro Modbus


Chas over at PNW/Electronics has been working on a PIC Micro MODbus project:

MODbus is a older-than-dirt communications protocol for industrial process/power controls. It’s generally seen in the wild as MODbus/RTU which is a RS-485 protocol ran at 9600 or 19200 baud. Of course there are a ton of variations and it wouldn’t be a comm protocol these days unless someone decided to make a MODbus/IP.. but that’s beyond the scope.

Continue to Update 2 – Calculating CRC and Update 3 – The 18F27J53 Port & tinyLED.

Join the Conversation


  1. Just to repeat what I posted to his website in regards to his wonder about Modbus/IP.

    Modbus/TCP is alive and well in the industrial Ethernet world, in fact Schneider Electric still uses it as a primary communications protocol, and almost every other vendor who deals in Ethernet connectivity has a ModbusTCP driver as it’s effectively open source, license free, and fairly lightweight. It’s just not natively deterministic (nor protected against attacks really). It’s also predisposed to allow the TCP module to act as a gateway to serially connected ModbusRTU units.

  2. I’ve used PIC and MODBUS for 15 years now it is still the most common industrial and control system communications protocol and is rock solid, very well documented (in a way you can understand – I’m looking at you USB!) and so simple it does not get in the way of your other code.

    Still used everywhere in industrial control, I just finished a PIC/MODBUS board for a client a few weeks ago I wish I could have open sourced it like some of my other projects, but sometimes you have to bite the bullet and take the cold hard cash :-)

    Very easy to read and nicely commented code BTW.

Leave a comment

Your email address will not be published. Required fields are marked *

Notify me of followup comments via e-mail. You can also subscribe without commenting.