Wonderware noob question

Hi all, new to PLCs and to Wonderware, but I'm learning. I have a question about displaying a historical value, not as a trend, just a value. I have implemented a rain gauge into the Wonderware HMI, but now I want to show a rain count for the past 24hrs.

The rain gauge simply counts up by 1 whenever a small bucket is filled. So, the input to the PLC (Unity Pro xl, Schneider Quantum) is just +1. I have converted that to mm for the HMI display, which works.

How can I also display a count for the previous 24 hrs? I know I could display a trend, but just want to display the number.
Make any sense?

Thanks, looking forward to being a part of the forum.

Use a memory tag and make a data change script to +1 the memory tag. Then do a conditional script for at time X (whatever time you want your contract hour to be) make another memory tag = your counter memory tag. and display that number

Instead of the ww script just do it in the plc. Use the plc clock to accumulate a value every hour.

robertmee said:

Instead of the ww script just do it in the plc. Use the plc clock to accumulate a value every hour.

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robertmee is correct on this. The right way to do it is in the PLC. The HMI should really be to display the information and to interface. Actual scaling and calculation should be done in the PLC. However if you REALLY want to do it "with wonderware" it can be done with a couple Memory tags and some simple scripting.

Yeah, do as much as you can in the PLC. Altering values/scaling/making calculations in Wonderware may be easier for some people, but can lead to confusion when troubleshooting, as your troubleshooting guys will start at the PLC....

do this in the plc. Have the logic fill in values into memory locations and the wonderware graph display them. Setup a FIFO. Wonderware probably can do this but it is best to keep stuff like this off the HMI.

Thanks guys. All of that is pretty well over my head, but it gives some direction and stuff to look up.

Just my opinion. But anytime you do time based functions in a PLC you need to have automatic time synchronization. This allows your functions to works as they should even when CPUs are replaced or PLCs are powered down ect.

Personally i would do it from Historian like you suggested initially. I would suggest looking at the aaHistClientQuery control.

That should be a push in the right direction.

RheinhardtP said:

Just my opinion. But anytime you do time based functions in a PLC you need to have automatic time synchronization. This allows your functions to works as they should even when CPUs are replaced or PLCs are powered down ect.

Personally i would do it from Historian like you suggested initially. I would suggest looking at the aaHistClientQuery control.

That should be a push in the right direction.

Click to expand...

I would argue that PCs are down far more often than a PLC and relying on data capturing means data loss when that occurs.