Hi Guys,
In some of my ladder logic in a program I wrote I have used several ONS instructions. None are tagged the same so there is no issue with crossing. Anyway part of my program operates an ONS which then resets several counters. This section of ladder logic is run by the system approximately 30 times per day 6 days per week and this issue has crept up just twice in the last 10 days. (The system has been live for approximately 3 weeks now). What appears to be happening is the ONS seems to activate but not reset so the next time the section of ladder is operated it won't activate. It is extremely important for this not to happen as the whole system cannot carry on until the counters are reset.
When I looked at the ladder logic I realised that I didn't have any real need for the ONs instruction so I've removed it now and time will tell if this solves the problem.
My question is this; can a ONS 'stick' for no apparent reason? Or even can the processor miss the scan the ONS was supposed to operate on?
Any advice would be a great help for future programming. I have found that ONS instructions tend to be a little hit and miss with RSL5000.
In some of my ladder logic in a program I wrote I have used several ONS instructions. None are tagged the same so there is no issue with crossing. Anyway part of my program operates an ONS which then resets several counters. This section of ladder logic is run by the system approximately 30 times per day 6 days per week and this issue has crept up just twice in the last 10 days. (The system has been live for approximately 3 weeks now). What appears to be happening is the ONS seems to activate but not reset so the next time the section of ladder is operated it won't activate. It is extremely important for this not to happen as the whole system cannot carry on until the counters are reset.
When I looked at the ladder logic I realised that I didn't have any real need for the ONs instruction so I've removed it now and time will tell if this solves the problem.
My question is this; can a ONS 'stick' for no apparent reason? Or even can the processor miss the scan the ONS was supposed to operate on?
Any advice would be a great help for future programming. I have found that ONS instructions tend to be a little hit and miss with RSL5000.