Write Out to PLC when Alarm Status Changes

Write out to a PLC address during an alarm event. In a common scenario, a PLC is used to trigger a siren, klaxon, illuminated beacon or some other local event to alert operators. Once the alarm has been acknowledged, the PLC stops the alert.

Using an Alarm Status Tag and an I/O & Calculations Tag

A simple way to do this is to create a tag that will monitor for unacknowledged alarms and a second tag that will write out to the PLC when the conditions are met. (ie. alarms acknowledged.)

1. Create an Alarm Status tag.

   1. Configure it with the necessary filters for priority, area and name.
      

   2. Set the Alarm List to "Unacked".

      

2. Create an I/O & Calculation tag.

   1. Set the Data Type to "Digital"

   2. Check the "Calculation" check box.

      

   3. In the Calculation tab, set the Calculation field to "tag" mode and select the Alarm Status tag.

   4. Set the I/O Device and address appropriately to write to your PLC.
      

The Alarm Status tag's value will become TRUE when there are unacknowledged alarms that meet the set filter criteria, and FALSE when there are not.

Related information:

Alarm Status Tags

I/O and Calculations TagI/O and Calculations Tag