So, today, I want to tell you about a PLC project I did for a large industrial factory during the mid-1980s.

The purpose of the project was to replace a set of mechanical relays and discreet analog devices with a programmable process that would control solid-state relays and replace a bunch of individual temperature controllers and load cell PID controllers. I used a Gould Modicon PLC for the project.

It was an interesting challenge, especially because the company didn't have any schematics for the existing system. The first thing I had to do was figure out what was going on, and build out a set of schematics based on my observations. Many times during this effort, I sat down with engineers that knew what should be taking place. I showed them what I thought was actually taking place. Both the company's engineers and I would often be shaking our heads as we walked away from these meetings.