Hi. I'm a beginner at programing and my question is about the MOV instruction at RSLOGIX.
First of all I dont have any practicals issues with this question, it is more related to understanding how a PLC scan works.
I got a program from a client and now this program is offline. A MOV instruction has a source value of.. let's say.. 30. But the destiny here has a value of 40 while the program is off.
My first thought on this subject was that the program should have other instructions using the destiny tag before the end of the program. But I checked it and didnt see any instruction related to it.
So the only other thing I could think of is that when the PLC took the picture of the values to show it on the screen, maybe it got the processed value from the destiny tag, but a newer value of the analogic input (which is the source tag) that is now different from the value used to move to the destiny tag earlier.
Is that how it really works or am I getting things here wrong?
First of all I dont have any practicals issues with this question, it is more related to understanding how a PLC scan works.
I got a program from a client and now this program is offline. A MOV instruction has a source value of.. let's say.. 30. But the destiny here has a value of 40 while the program is off.
My first thought on this subject was that the program should have other instructions using the destiny tag before the end of the program. But I checked it and didnt see any instruction related to it.
So the only other thing I could think of is that when the PLC took the picture of the values to show it on the screen, maybe it got the processed value from the destiny tag, but a newer value of the analogic input (which is the source tag) that is now different from the value used to move to the destiny tag earlier.
Is that how it really works or am I getting things here wrong?