Factorytech on Blog | Jonas Neubert

The Best Python Packages for Reading Barcodes

Fri, 30 Sep 2022 00:00:00 +0000

Three years ago I published a blog post on how to generate barcodes using Python. It’s one of the most visited posts on the blog! Occasionally a reader emails to ask: “But what if I want to read/decode/scan¹ a barcode, not write it?”

Here is the answer:

Don’t use Python for Barcode Decoding!

You really shouldn’t be using pure Python to decode barcodes from images or videos or, worse, from camera streams.

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.

The Best Python Packages for Generating Barcodes

Wed, 23 Jan 2019 00:00:00 +0000

Barcodes are a cheap and ubiquitous way to add machine-readable information to an object. I think of barcodes as the real-world equivalent of browser cookies: For example, when you arrive at airport departures, the airline hands you a boarding pass with a barcode (the cookie). From that point onward you’re asked to show your barcode at every interaction: at security, the duty-free shop, and the boarding gate. And just like the information stored in browser cookies, the information in barcodes isn’t in plain sight but easily made visible.

PyCon 2017 Talk

Sat, 10 Jun 2017 00:00:00 +0000

The PyCon talk which I’ve been preparing for with steadily increasing stress levels since February happened three weeks ago at PyCon 2017 in Portland. Time to post a quick retrospective!

The recording of the talk is up on Youtube. Huge props to the PyCon organizers for posting all talk recordings publicly every year. This year the videos were up less than 24 hours after the talk!

I also put together Github Gist with links and notes to go along with the talk, and the slide deck is up on Speakerdeck (although the slide deck only covers what was on screen for half of the talk, the other half consisting of the demo).

PyCon Talk Progress Update: Hindsight is 80/20

Thu, 27 Apr 2017 00:00:00 +0000

The high level update on my PyCon talk prep is that I’m currently making the transition from making steady deliberate progress to a more panic-driven hair-on-fire style of working. Three weeks from today this thing better works–on stage, and in Portland.

On a more technical level, the status is that I have a working prototype of my demo and am confident that I can construct a good talk narrative around it. Here’s what the prototype currently looks like (cat for scale):

PyCon Talk Progress Update: What needs to be in a Robotics Demo?

Mon, 13 Mar 2017 00:00:00 +0000

It’s been a month since my factory automation talk got accepted into PyCon. If you’ve been following along by means of this blog you’ve seen that I bought a barcode reader on Ebay, made an adapter for it and wasted some time figuring out how to do Serial-to-USB on a Mac.

Barcode readers are cool stuff, but when you promised a factory automation demo, reading a few barcodes doesn’t really cut it. The same goes for a lot of other automation equipment like pushers, shakers, label printers and so on: It might technically be factory automation, but nobody comes to PyCon to see tech that contains fewer transistors than the blender in their kitchen at home.

One simple trick for USB-to-Serial on MacOS X

Tue, 07 Mar 2017 00:00:00 +0000

Call me a Luddite if you wish, but I lament the lack of serial ports in modern laptops.

My relationship with USB-to-Serial cables has been one of disappointments, crashed computers, and garbled data. The one I pulled out of a drawer this week randomly flipped the most significant bit of every character. How do I know this? Because I wasted three long nights debugging the problem.

But I’m a changed person now because I learned this one amazing trick for making USB-to-Serial just work on macOS:

MS3 Adapter for Serial Port and Power

Mon, 06 Mar 2017 00:00:00 +0000

In last week’s post about barcode readers I mentioned that I purchased an MS3 from Microscan for my PyCon demo. What I had forgotten from last time I worked with the MS3 is that the pin-out of cable attached to the barcode reader is not just a DB9 (nine pin) serial port connector but a DB15 (VGA style) plug. Those extra pins are used for sending power to the device and to accommodate a few extra features, namely trigger and reset inputs.

Intro to Barcode Readers

Sun, 26 Feb 2017 00:00:00 +0000

If you read last week’s blog post you already know that I’ve got three months to put together a physical demo for a PyCon talk about factory automation. This post is the first in a series of progress updates.

In robotics and automation, the smallest realistic demo has three parts: Sensing, control, and actuation. I spent Week 1 selecting and bargain hunting for an industrial barcode reader to cover the sensing part of the demo. As I went along I wrote up my notes as an “Introduction to Barcode Readers”; if you only want to know what I ended up buying, scroll down to the end!

Tap, Tap, Tap

Sun, 12 Feb 2017 00:00:00 +0000

… is this thing still on?

Besides that Tumblr blog where I collect factory flicks on a NSFW domain, I haven’t produced much written content for public consumption over the past three years. Looks like they even shut down Google Reader because this blog dried up!

But things are about to change! Here’s the plan:

My talk proposal for PyCon 2017 just got accepted (via a detour through the backup talks list). The title that my pressure prompted brain came up with a few hours before the submission deadline: