Scaling wonderware analog values

[al wick]

I'm trying to read temperature values into Wonderware Intouch from my plc. It won't allow me to scale these values, as they are inverted. A plc value of 1 = 226F, Value of 4096= 13F. It expects the opposite.... large plc values to result in large temperatures. So I get the error message that Min EU must be less than Max EU (engineering unit).
I'm using IOServer to interface to plc.

I am able to accomplish this by using slope formula in wonderware, but I want to do it using the scaling function when defining the tagname.

Sure appreciate any suggestions.

Thanks
-al

 

[rdrast]

Bug in WonderWare, that has been there forever.
Define the tag normally, or with no scaling, and set a "data change" script up on it. Scale in the data change script to a new memory tag.

 

[al wick]

Thanks. I was simulating this in spreadsheet. I also have option of using plc program to just subtract the value from 4096, then sending that to Wonderware. This allows Wonderware to accurately scale the value with no error messages. Think I'll do that.

-al