|
Some fairly simple techniques can be used to fault find the PLC, the easiest is probably the half split technique. This however relies on knowing where the various test points are for the PLC system. Our courses are based on understanding simple diagrams and then using them to fault find, delegates cannot believe how simple it is once you know where the test points are and how to test them and are then confident to say wether the signal is present or not. Test a point and then go on. 8 simple test points and you know where the fault is. There are 3 places where the PLC program can reside, you need to know where they are and how to keep them all the same, not easy with some PLCs. Where is the problem, how do I know the PLC is OK. The Led on the output card means i am getting voltage out right? does it? What exactly happens in between? ,theres more than just a program in the CPU How exactly does it scan the program? Do I need to know? What is this Watchdog Timer? Is it that important? Can I use the same output twice? That's bad programming isn't it? A PLC is a logic controller, so use a logical approach to fault find it. What are the 5 points to check without a laptop? What are the 8 simple test points to check? The PLC is in RUN, that means theres a program right? does it? FORCING a bit and toggling a bit is pretty much the same yeah? depends on which PLC
Our delegates are always amazed that by following the logical approach we teach works every time.
Within the first hour of the course delegates are able to identify exactly where the problem is within the PLC Control System.
|
