FactoryTalk SE Tag Issues etc.

Hi Guys,

Looking for some advice on how to approach this as I feel i'm really making a mess of this.

I have an SE application communicating to 11 CLX L-55 PLCs. There are a large number of numeric displays which I total values from each PLC etc. The problem then arose when a PLC lost comms or was powered down that the numeric display wireframed and my calculations were also wrong.

I started to then use derived tags and using the expression : If COMM_Err PLC tag then 0 else PLC Tag is equal to Internal tag. The problem now is Im going to have tonnes of derived tags each checking for comms and tranferring data into Memory tags for calculations.

Has anyone any suggestions for this? If a PLC is lost can SE not just write 0 to these values by default?

My main concern is I have a lot of calculations to do and its going to get very messy.

Hope this explains what I am trying to achieve.

Why not do all the calculations in one of the PLC's and then just display the values on the screens. I have never liked doing calculations in the HMI.

I agree completely. Problem is Plant is up and running and I'm told this is the way it is.

Gotcho said:

Why not do all the calculations in one of the PLC's and then just display the values on the screens. I have never liked doing calculations in the HMI.

Click to expand...

Gotcho, I agree with you, but what about if they also lose comm with that plc. It would be better to find out why they are losing comm and try to avoid that. What about comm switch for instance, have they check if it´s compliant with AB requirements ??

So other than doing this in the PLC I have no other options?