I was troubleshooting a very irregular network interruption between two industrial controllers (AB PLC and a DCS). For those who do not work in industrial automation communication between assets is essential and some disruptions can be quite costly depending on the industry/product being made. That can be true of even relatively minimal disruptions.

I loaded up an RPi with arch, popped a thumb drive on there and created some startup scripts. Once the RPi booted up it just performed a rolling packet monitor. Once I was alerted about a disruption I went and grabbed the thumb drive. I found a Modbus TCP driver bug.

What’s even better is I ended up ‘packaging’ it in an enclosure and was able to utilize it in a lot of scenarios. I’ve been using it over the past 2 years.

Edit: in the industrial world equipment like this is not in racks/server rooms. They are usually located in panels that have no external networking (security). When I ‘grabbed’ that means traveling to the site and literally taking the drive.