Machine Safety: an automatic sequencer does what?

In the world of machine control and machine safety, to really appreciate where we are today, don’t we need to have a reasonable understanding of where we’ve come from?


In the world of machine control and machine safety, to really appreciate where we are today, don’t we need to have a reasonable understanding of where we’ve come from?

I’m one of the few people active today in industry that witnessed the installation of PLC 1’s in an automotive plant in Ohio. This was actually two plants in one on the Lake Erie shore that produced sixty automobiles and 30 light trucks per shift hour six days a week. As a young engineer in 1968 I was totally amazed at how the complicated machinery, conveyors, and multiple systems would all simultaneously start at 6:00 am. Every control system was hard wired and software was nowhere to be seen on the factory floor.

Yet, also in 1968, a small band of Detroit engineers at General Motors Hydra-matic were looking for a standard machine controller. They wanted a programmable standard control system that would replace all the electro-mechanical (relay) panels and direct wiring. They prepared bid specs and recruited four companies: Allen-Bradley, Digital Equipment Corp. (DEC), Modicon and Century Detroit. Alas – this was the beginning of what we now call Programmable Logic Controllers (PLCs). And, in the early 1970’s when several PLC’s arrived at our automotive plant the maintenance staff first called them automatic sequencers because they did what relays did automatically. This is intentionally a very brief history of the development of PLC technology for machine control. Yet, in comparing PLC machine control technology from its meager beginning over four decades ago to the vast level of technology available today one can easily understand how we became the industrial leaders we are today. And most recently, machine safety / guarding has joined (I say, re-joined) the machine control automation architecture. This fact alone is a complete story still unfolding.

So, today we see an abundance of articles on safety communication systems, safe wireless, safe motion control,……..and more. All of which when properly applied can improve OEE and potentially lead to a new competitive advantage for your business.

Thank you – Automatic Sequencers!

Your comments or suggestion are always welcome so please let us know your thoughts. Submit your ideas, experiences, and challenges on this subject in the comments section below. Click on the following text if you don't see a comments box, then scroll down: Machine Safety: automatic sequencers do what?


Related articles:

Rockwell Automation (Allen-Bradley) – 1995 – PLC 25 Years

The History of the PLC, by Dick Morley     

The Birth of the PLC

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