Unitronics in General Motors

Entry posted by Matthew October 7, 2010

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An interesting thing happened to me a couple weeks ago. Well, let me back up...

We prefer to do all our control system design around the Unitronics Vision line. Specifically, we've found the V350 and V570 products to be the most suitable for typical applications. They're simply the most economical, full-featured products out there.

So when we were approached by a new customer to help with their machine controls we immediately thought of Unitronics. Simple application, really. Just use the PLC to control a VFD to rotate an arm 180 degrees at a time. A handful of digital I/O, nothing fancy. There would be some interfacing with another PLC-controlled device called an automated guided cart (AGC) just to keep things interesting. That's when they dropped the bomb: the main customer for this new machine is General Motors...

Well, that throws out Unitronics, right? Certainly General Motors will insist on Allen-Bradley. Since we also build the control panels, I was also worried they would spec every component down to terminals. I was only partly correct. They did spec the PLC and VFD to both be Allen-Bradley but they were very flexible with all the other components.

Okay, all this is just background so my main point will make sense. I did the design work, programmed the MicroLogix PLC, our shop built the panel and we were ready for startup in Grand Blanc, Michigan. Two minutes after arriving and setting up my computer, the AGC we're about to interface with drives up and there's a V350 staring me in the face!

That's right, here I was programming the despised MicroLogix controller and working side-by-side with a Unitronics product in a GM plant. That was pretty cool, I thought. Turns out the AGC was exempt from the Allen-Bradley spec because it's a portable piece of equipment and not technically installed in the plant. Good for them - perhaps this AGC will serve them well and it will lead to loosening the reins on PLCs a little. One can hope...