Unlike some safety PLCs on the market, ABB's AC500-S Safety PLC has a separate safety processor.
The Safety CPU can be configured to work even if the non-safety processor is in STOP or maintenance mode, or during an online change. (Source: ABB)
That's a good question Evanskollmorgen, especially since it's logical that customers will default to their PLC provider. Then it becomes a matter of trusting your PLC provider. But what are the alternatives?
Nice article, Al. Boy, it's surprising how much safety has changed in recent years. It wasn't very long ago that the idea of running safety and control on the same cable was considered a crackpot idea. Now you'd have to be a crackpot not to do it.