FT the global Connection remote display number

Hello everyone,
I have one question for old project FT. the global Connection remote display number, its set is
If NOT {PLC_Communication_Lost} Then {[PLC]HMI.commanded_page_number} Else 100

my question is : where PLC_Communication_Lost comes from? obvious it is not PLC tag, otherwise it should be {[PLC]PLC_Communication_Lost....} and in plc code should may find it. but can't.
In FT, how can find it(PLC_Communication_Lost)? where it be set?

Thanks!

It will be a HMI tag. If I had to guess, I'd say that this tag is used in an event driven macro, which is called every second using the system/seconds tag, to monitor a heartbeat tag from within the PLC, and if it doesn't change for x seconds, then the connection to the PLC is lost.

Check the HMI tag browser in FTView Studio, you should find the tag there. Then a simple find will probably tell you where else it is used.

ASF said:

It will be a HMI tag. If I had to guess, I'd say that this tag is used in an event driven macro, which is called every second using the system/seconds tag, to monitor a heartbeat tag from within the PLC, and if it doesn't change for x seconds, then the connection to the PLC is lost.

Check the HMI tag browser in FTView Studio, you should find the tag there. Then a simple find will probably tell you where else it is used.

Click to expand...

you are right, Thanks a lot!!

No problem!

Just for my own curiosity (and, let's be honest, to stroke my own ego a little), how close was I with regard to where and how the tag is used?

ASF said:

No problem!

Just for my own curiosity (and, let's be honest, to stroke my own ego a little), how close was I with regard to where and how the tag is used?

Click to expand...

you are right.
in global connection Remote macro 1 use system/seconds tag
then at project tree logic and control , define HMI tag PLC_Communication_Lost, then expression this HMI tag with second and PLC tag to indicate that which condition is PLC communication lost. next use this bit at global connection remote display