RMA
Member
I don't know, but I suspect it's got to do with my general problems with getting my head round the cyclical nature of PLCs in general!
As long as the timer's being started by a plant event, everything's OK. The trouble starts when I need to provide the edge-trigger to start the timer myself. Either I finish up with the Trigger signal permanently set, so there's no edge, or I finish up resetting it as soon as it's been cleared so that the timer keeps getting re-started!
I've just spent nearly an hour trying to get a simple impulse timer to work and still haven't managed it!!!
The trouble really starts, as in this case, when the FB has to run continuously, I can usually solve it when I'm only calling the FB on demand.
Can some kind soul please show me the definitive way to provide an edge-trigger to start a Timer (impulse in this case) and how to safely reset the trigger Bit afterwards, preferably in an FB using STATs.
Many thanks in advance from an extermely frustrated (not to mention embarassed)
Roy
As long as the timer's being started by a plant event, everything's OK. The trouble starts when I need to provide the edge-trigger to start the timer myself. Either I finish up with the Trigger signal permanently set, so there's no edge, or I finish up resetting it as soon as it's been cleared so that the timer keeps getting re-started!
I've just spent nearly an hour trying to get a simple impulse timer to work and still haven't managed it!!!
The trouble really starts, as in this case, when the FB has to run continuously, I can usually solve it when I'm only calling the FB on demand.
Can some kind soul please show me the definitive way to provide an edge-trigger to start a Timer (impulse in this case) and how to safely reset the trigger Bit afterwards, preferably in an FB using STATs.
Many thanks in advance from an extermely frustrated (not to mention embarassed)
Roy