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.
In reply to Youssef.El-Bahtimy: