In state driven EMs I am able to set my sequence (execution order) for all the states, but am I somehow able to set my sequence order for each individual state?
For example, lets say I have a pump with a downstream and upstream valve. When I start the pump, I would like to open the valves first, then start the pump. On the other hand, when I stop the pump I would like to stop the pump first, then close the valves. So between the "Start" and "Stop" states in the EM the execution order is effectively reversed. While there are plenty of workarounds, being able to set the execution order per state (rather than for all the states in the EM) could save a lot of configuration headaches.
This not only applies to pumps, sometimes I'd like to open a valve before the rest, but on closing I'd like it to be first to close. I can't imagine Emerson would not have this functionality in their EMs.
Matt,
You only have two choices:
- List the driving of the pump/valve SP multiple times and ignore the ones to get the operation required for each state
- Move to using a Command Driven EM which can do whatever you want as you are in control of the logic and the order it executes for each Command State.
We very rarely use these EMs because of this limitation and other technical reasons.
Your request to be able to set the order per state is probably not alone asking for this enhancement request for these EM types. You can submit this or any other enhancement request to the User Driven Enhancement Program at www.userideas-emerson.com.
Regards,
Matt