Plc on Blog | Jonas Neubert

Using pymodbus to communicate with a PLC

Sat, 02 Nov 2019 00:00:00 +0000

This post is part 4 of a series covering material I presented in a talk at PyCon 2019.

In the previous parts of this series, I covered what a PLC is, and how PLCs are programmed. In industry, the Python developer is usually not involved in the purchasing, installing, and programming of a PLC. If you find yourself working with PLCs in academia or for a hobby project, you might actually be the one doing these things yourself. Either way, I assume that you somehow found yourself with a programmed PLC and now want to connect to it using Python.

Ladder Logic‽

Tue, 29 Oct 2019 00:00:00 +0000

This post is part 3 of a series covering material I presented in a talk at PyCon 2019.

Most software engineers are used to writing text-based code using a text editor of their choice. Things work a little bit differently in the world of PLCs. To program a Programmable Logic Controller (PLC), you can’t just open up your favorite text editor and start typing away PLC code. First, PLC logic isn’t programmed in text (exceptions apply, see below). Second, you can’t use your favorite programming software; instead you will be using the one programming software that the vendor of your PLC provides.

What is a Programmable Logic Controller?

Mon, 28 Oct 2019 00:00:00 +0000

This post is part 2 of a series covering material I presented in a talk at PyCon 2019.

I have prepared three different conference talks about PLCs for Python programmers. Annoyingly, you can’t assume that every Python programmer knows what a PLC is, so I always have to sacrifice a few minutes of my time slot¹ to convey the basics before diving into my actual topic. This blog post is the content I have settled on for those first five minutes of my talks.

What is a PLC and how do I talk Python to it?

Sun, 27 Oct 2019 00:00:00 +0000

This post is part 1 of a series. Scroll down for a table of contents.

If you’ve found your way to this blog, chances are you already know that I’ve given a few conference talks about using Python in automation. You are right now reading the blog post version of content I presented at PyCon 2019. I started my talk there by answering the question: Why do I keep talking about this topic?¹

List of PLC brands and products

Sat, 27 Apr 2019 00:00:00 +0000

tl;dr: Here’s the link to the spreadsheet.

I’ve been thinking about Programmable Logic Controllers (PLC) again recently, not least because I am preparing a conference talk about them. While putting together the presentation I thought to myself “Why not make a list of PLC products out there, I wonder how many there are‽”

Turns out, there are quite a few! After three evenings of research I had a spreadsheet of 144 product lines. That number shouldn’t be a surprise given that this is a 50-year-old technology that is ubiquitous in factories, infrastructure, and machinery.