2stepsforward
Member
I have a small project where I need to replace an electromechanical cam timer (something similar to these: https://micronor.com/products/cam-timers/) with a PLC.
However, key to retaining similar functionality to the current system, I need the output contacts from the PLC to remain in their previously set positions throughout a power loss/ PSU or CPU failure scenario. Any thoughts how this could be done?
I was thinking using separate latched relays with Set and Reset coils for each output, but this has some sacrifices in terms of space and then having a power-up or First Scan bit to allow realigning the PLC code with the desired cam position. It would be acceptable to have operator input through an HMI to align the PLC mode/ step or time with the desired set before resetting via another input.
Hardware is likely to be based on an A-B Micro8## or MicroLogix platform, though other options exist.
Any other smarter solutions?
However, key to retaining similar functionality to the current system, I need the output contacts from the PLC to remain in their previously set positions throughout a power loss/ PSU or CPU failure scenario. Any thoughts how this could be done?
I was thinking using separate latched relays with Set and Reset coils for each output, but this has some sacrifices in terms of space and then having a power-up or First Scan bit to allow realigning the PLC code with the desired cam position. It would be acceptable to have operator input through an HMI to align the PLC mode/ step or time with the desired set before resetting via another input.
Hardware is likely to be based on an A-B Micro8## or MicroLogix platform, though other options exist.
Any other smarter solutions?
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