arkansascontrols
Lifetime Supporting Member
I have an S7 application that was acting strangley.
I had a symbol at some memory address M9.5 that was used previously but eventually freed up, and cleared from the symbol table. Later I had an occasion to need a new permissive and got the next available M address which happened to be M9.5. The new logic that set the bit was working properly and the bit was high as it should have been, but a subsequent rung that contained an XIC (Normally Open Contact for you non AB users) although it showed true the logic that followed would not execute.
Once I changed the address of the bit to M9.6 the rung that used the bit as a permissive began working. I discovered this by branching around the bit with an ALWAYS TRUE input. Even though it was true the logic would not execute, but with the always true in parallel, the rung would execute.
I've also noticed that if you delete an FC and then later create a new FC using the original FC Number when you download it to the PLC you get a warning that it exists.
Is there a way to 'clean up' the memory so to speak to truly rid it of all previously deleted routines and tags?
Eric
I had a symbol at some memory address M9.5 that was used previously but eventually freed up, and cleared from the symbol table. Later I had an occasion to need a new permissive and got the next available M address which happened to be M9.5. The new logic that set the bit was working properly and the bit was high as it should have been, but a subsequent rung that contained an XIC (Normally Open Contact for you non AB users) although it showed true the logic that followed would not execute.
Once I changed the address of the bit to M9.6 the rung that used the bit as a permissive began working. I discovered this by branching around the bit with an ALWAYS TRUE input. Even though it was true the logic would not execute, but with the always true in parallel, the rung would execute.
I've also noticed that if you delete an FC and then later create a new FC using the original FC Number when you download it to the PLC you get a warning that it exists.
Is there a way to 'clean up' the memory so to speak to truly rid it of all previously deleted routines and tags?
Eric
