There may come a time in your career when you are called to investigate a malfunction in an existing control system that someone else has written. The field device documentation may be scarce or even nonexistent and you don’t know what field device belongs to which address. You could press each s...
In this lesson we are going to show you how to modify a value in the PLC. You are working on a new plant and you have a line of logic that is looking for a particular field device to be true before the logic will solve true but that field device isn’t yet installed. Let’s say that you need a valv...
In this lesson we are going to discuss a method to change the status of an input address. As we’ve discussed previously, the CPU first scans the inputs and puts the statuses or values within a memory area in the PLC. The scan then solves the logic based on the input statuses. And finally, the CPU...
