Adding an alarm to an existing S7 300 project

Hi guys, I'm new to this forum. I'd like to add an alarm code to an existing S7 project. The signal is from a normally closed contact of the sensing unit. This alarm will have a mimic on a SCADA station. Can anyone help me with the S7 code

On an existing system you would follow "how it's done now". Look at your program for PLC and HMI and tell us how it works now. If you don't know how it works now, ask questions and we will help you figure it out.

Ultimately a bit in the plc tells the hmi the alarm is present.

Welcome to the forum!

Is this a standard HMI (Screen)
or a full SCADA eg Citec or other?
If it's not a standard screen there may be issues with tag lisences.