I want to put an alarm off of the output parameter of a PID block, when the output is greater than 50. The issue is when i try to add an alarm off the PID1/OUT I cannot set the limit value or parameter. I have been relegated to using a comparator block and a Boolean bit to trigger the alarm. The issue is that the operator does not know what the alarm value is, I can try to get clever and put the alarm value in the alarm name but I am hoping for a better solution than this.
Thank you in advance
I would look at the following thread for an in depth discussion on standard vs. custom alarms. http://community.emerson.com/process/emerson-exchange/operateandmanage/deltav/f/50/p/4355/9570#9570
My suggestion is to wire your PID/OUT to an ALM (alarm detection block) and then select 'Assign Alarm' on the alarm detection block. This will give you all the features of a 'Standard' alarm. PID/OUT cannot be assigned to a standard alarm directly.
Trying to configure a custom alarm off of PID/OUT will cause problems for you. The configured parameter for the Related Parameters / Alarm field in the Alarm properties dialog is a boolean representing the alarm evaluation state, so you would have to first evaluate your PID/OUT against a limit, then enter the parameter evaluating true/false in the field. The alarm detection block, and any other standard alarm type blocks, provide these as an _ACT parameter and automatically associate the limit parameters, message parameters, etc. PID blocks can Assign the PV to High, Lo, deviation etc. alarms, but not the OUT.