Innovation by its very nature causes many common things to become obsolete. The steam locomotive replaced by diesel. The horse and carriage replaced by the automobile. The relay panel to be replaced by the PLC and the PLC is replaced by faster, networkable and data ready PLCs and controllers.
One of my favorite stories about obsolete hardware started about 10 years ago. I will change the names and places to shield the guilty. I got a call at home on a Sunday from a familiar client and he was in a jam. He was restarting his production line after a planned outage and one of the key lines would not start up. He thought maybe it was a Modicon PLC and would I please come out right away and help. I have done some Modicon programming but it was Sunday, his details were sketchy and I had some plans at home. He sweetened the pot by telling me that he had another person coming to help. That guy just happened to be my Uncle. Working with my Uncle sounded like fun so I agreed to come and have a look but no promises.
I beat my Uncle to the plant and by the time he arrived I had found out that the PLC was an original Modicon PLC that should really be in the Smithsonian or on Dick Morley’s mantel . I had never seen one before and was amazed that it was still working; at least until very recently. I pulled this old controller out of the panel and found that the circuit boards were completely smoked. A little more investigation revealed that the panel was not grounded properly and a short circuit had fried the ancient controller. My Uncle showed up and agreed about the cause and effect and also joined me in lamenting the death of such a rare and historic controller. He worked in maintenance at a large multinational and knew that they had used the same controller at one time. One by one theirs had been replaced by newer technology.
Together we explained the problem to the client and told him that there was no way to source a replacement controller. An upgrade was necessary and would be a little more time consuming. His production would be stopped for at least a week at best. The client was not happy but could see the damage to the controller. He had trouble believing that his technology could be so out of date but accepted the facts as explained by two controls experts. We asked him what he wanted to do. We were surprised when he said “hop in the cart”. We hopped into his golf cart and sped off across the plant. The client pulled up to an area that was full of spare equipment including panels and drives as well as mechanical bits and pieces. He jumped into the pile and to our absolute shock he pulled out another controller the exact same as the one that had been blown.
I had heard of these controllers but never in my life had I seen one and now I had seen two in the same day. My Uncle and I worked into the evening and by 7:30 had the machine up and running again. Luckily my Uncle still had the old programming terminal from his work and there was a PROM card with the program on it in the machine when it blew. (Programmable Read Only Memory)
Despite my many warnings to upgrade the machine the client only saw it running and refused to believe there was any issue now. Each day every controller in industry get older and the day is coming when all of these controllers will fail. I am afraid that too many companies are banking on being able to pull one out of a hat like this client did. There are lots of other stories I could tell about upgrading control systems but they are pretty boring. Pretty boring is how they should be though with no surprises like finding and original PLC and then finding a spare to replace it. I have never seen another one.