Can we use Ignition as Inter-PLC Communication between several PLCs where we don’t have to use messaging? Can we send/read data from one PLC thru gateway then pass it to the other PLC?
Yes, use transaction groups
but only for non critical data.
thanks for the reply bro!!!
[quote=“Chris Taylor”]Yes, use transaction groups
but only for non critical data.[/quote]
+1 on that.
Good design practice is to never have a more reliable device rely on a less reliable device.
+1
I can't tell you how many times I've been tasked with upgrading a system to a different HMI package only to find out that it had extremely critical data being computed in the HMI and then relayed to a different PLC. It's a nightmare full of non-euclidean logic and dead-ends in dark alleys where bad things happen. 
For PLC-to-PLC communication where the two devices cannot communicate to each other natively, you might want to check out something like the Red Lion DSPLE it's less than $600 last I checked and a more robust solution than HMI based communications