how we get this alarm signal in PLC. we need to link this alarm signal with database address so that if the alarm come in SCADA , it will also transfer to PLC for some interlock
Example- If High High alarm comes ( when process value crosses 90 ), the High High alarm will come. that alarm we need to link with Database address so that PLC also used this alarm signal as an interlock.
So please suggest how to link this alarm with the database address.
You should be isolating your SCADA from your control logic.
You should NOT rely upon the SCADA to perform control functionality, it decreases the reliability of the overall system, and complicates diagnostics.
The recommendation would be to push the High High Setpoint into the PLC, and allow it to be changed from SCADA. The PLC will then do the comparison between the PV and the High High SP, and perform the control action based upon this.
Lead Control Systems Engineer for Alliance Automation (VIC). All opinions are my own and do not represent the opinions or policies of my employer, or of my cat..