Industrial control programming and protocols on a Raspberry Pi
Modbus Writes from Node-RED
I modified the earlier ladder logic program to light the LED from either the pushbutton or a holding register (%QW1
; Figure 12), which is an integer, so the value is converted to a boolean then OR'd with the pushbutton interface. The result of this OR is the value of the LED.
On Node-RED, a slider
node is used to pass a 0 or 1 to a modbus tcp output
node, which is configured as a single write to holding register 1. After the Node-RED logic is deployed, the web dashboard is accessed at: http://<your_rasp_pi>:1880/ui/ (Figure 13).
Final Comments
Learning industrial control theory can be a little challenging: It's a very large topic with specific standards (e.g., IEC 61131-3 programming) and industry-specific communications packages like Modbus. Luckily, open source packages like OpenPLC allow you to familiarize yourself with industrial controls on low-cost hardware like the Raspberry Pi.
OpenPLC is an excellent testing and teaching tool, but it's important to point out that OpenPLC is not designed to be used on real-time projects that have environmental or safety concerns.
Infos
- OpenPLC documentation: https://www.openplcproject.com/
- IEC 61131-3 documentation: https://en.wikipedia.org/wiki/IEC_61131-3
- Node-RED documentation: https://nodered.org/
- OpenPLC install: https://www.openplcproject.com/getting-started/
- Modbus documentation: https://modbus.org/
« Previous 1 2 3
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.
-
XZ Gets the All-Clear
The back door xz vulnerability has been officially reverted for Fedora 40 and versions 38 and 39 were never affected.
-
Canonical Collaborates with Qualcomm on New Venture
This new joint effort is geared toward bringing Ubuntu and Ubuntu Core to Qualcomm-powered devices.
-
Kodi 21.0 Open-Source Entertainment Hub Released
After a year of development, the award-winning Kodi cross-platform, media center software is now available with many new additions and improvements.
-
Linux Usage Increases in Two Key Areas
If market share is your thing, you'll be happy to know that Linux is on the rise in two areas that, if they keep climbing, could have serious meaning for Linux's future.
-
Vulnerability Discovered in xz Libraries
An urgent alert for Fedora 40 has been posted and users should pay attention.
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.
-
New Pentesting Distribution to Compete with Kali Linux
SnoopGod is now available for your testing needs
-
Juno Computers Launches Another Linux Laptop
If you're looking for a powerhouse laptop that runs Ubuntu, the Juno Computers Neptune 17 v6 should be on your radar.