Hello najjarja:

I think you are looking to build what is called a "Performance Equation" tag in the PI world.

First you need to create the tag with your desired tagname and the proper pointsource, which is by default pointsource=C

Could you first see if you have any points on your system with pointsource=C? if so, have a look at the tag configuration. The main things to determine is your scan class, which is the frequency at which your sum will be performed (more on this later). This depends on the .BAT file of the interface and the scan classes you have identified. The 'labels' of the scan classes listed (there may be only 1) are simply their sequence - 1, 2, 3 etc in the order they appear. So pick your frequency and count its position. This integer needs to be in location4


After that, there are two very simple syntaxes for a sum for two points, say tagA and tagB

Do you want the sum to be calculated at a certain frequency, ie the one that you have specified in location4? ==> then use this syntax:

'tagA'+'tagB' (insert this in the Exdesc field)

Or, if you want the sum to be calculated only when the value of another tag changes, use this syntax:

event=tagC,'tagA'+'tagB' (tagC can be any other tag on the system, including one that is involved in the calculation.
If you want this behaviour, enter this syntax in Exdesc)

Save your tag and wait for either your scan rate to come around or your event tag to change, and you should see a value in your new tag. There are lots of other tricks you can do with "PE Tags" but this should get you started.

Important: if you don't have any pointsource=C points running on your server, we may need to back up and get the interface up and running first. If I remember properly it is not installed as a service by default.


let us know
douglas