CompactLX needs to know when PV+ is turned off

I have a L33 CompactLX PLC. I need to know if the PV+ turns off. Does the PV+ have a handshake bit I can look at?

Welcome to the forum!

Not exactly, but you can make something work.

You can run macro's at startup and shutdown, which could set a bit in your PLC to indicate as such. In the event that the screen loses power without going through a proper shutdown procedure, this won't work of course, so it depends on the details of what you're trying to detect and why.

A more reliable, but slightly more complex option is to create a macro which is event triggered. Tie the event trigger to the system/seconds or system/minutes HMI tag, so it triggers the macro every second/minute. Inside that macro, set a bit in the PLC to 1.

Assuming you use the seconds tag, the bit in the PLC wil be set every second. Run a timer in the PLC unconditionally, and every time the bit gets set to 1, set it back to zero and reset the timer. If the timer ever reaches, say, 4-5 seconds, your HMI has stopped.

I generally just configure a Global Connection in FactoryTalk View ME to write the value of the Seconds tag in the PV+ to a tag in the PLC; you can set those connections to write as fast as 1 second.

If that tag stays the same for more than a few seconds, I know the PV+ isn't running its HMI application.

Quick pit-stop...

"Seconds" away...

479656 - PanelView Plus heartbeat signal to controller
Access Level: TechConnect

"Macro" analysis...

34183 - Using a heartbeat to see if connection has been lost to a PanelView Plus terminal
Access Level: TechConnect

I prefer the "seconds" option. Just reading the "Method of operation" for the Macro option will leave you "tag-tied".

Regards,
George

Thank you! This all helps greatly.