How can an alarm be displayed on a RS485 network (bus terminal topology)?

FAQ #101544

 

Symptom
When an alarm arises and the display (e.g. a PCD7.D23x) is connected on an RS 485 bus, the screen of the terminal can't be forced in order to display the alarm contained in the buffer.

Reason
This restriction is due to the network configuration; several displays can be connected on the network but only one can communicate at once with the PLC (only one display can be operated). All other dispays are not operatable (they display "Busy menu")! While the displays are in a standby mode an alarm can't be displayed as "popup" on all displays!

Solution
In order to inform the operator that an alarm is present it is possible to display the general alarm flag on the standy menu.
It has to be configured as shown in the following screenshot: