RSview32 Tag temporarily buffered to another tag

[mawalters]

I am trying to take a value from one tag and hold it in another tag temporarily so I can then apply a comparison to the value that was held in the temp tag to an accumulated value generated over that same time.

For example... Lets say I want to take the height of a tank of oil calculate out the total barrels save that wait 10 minutes take the difference between the 2 barrel totals and compare that to how many barrels have flowed in or out of the tank since.

I have an idea of how I thought I could do what I wanted but I think now that the idea may be preventing me from seeing an easier way.

Thanks

 

[kamenges]

Soooo...what was your idea?

Keith

 

[mawalters]

The idea was the way I described first, with buffering a tag into another tag temporarily.

 

[JeffKiper]

Do the math in the PLC. That works for me. I don't like having alot of thingsgoing on in the HMI that is on a Microsucks platform. You know where that is coming from.

 

[Lancie1]

Mawalters,

In RSView there are tags called Defined Tags. These are internal tags that are calculated based on the value of other normal external-value tags. You could used a Defined Tag to hold your temporary value. Finding a way to trigger the transfer of the data will be the hard part. Probably you can use an If conditional statement for determing when to transfer data to and from the temporary tag.

 

[Honga]

I would do this in the plc personally.

If you have the processing power you could do a running average
while(1)
Old_Average = Average
Average = (Old_Average + New_Value)/2
end while

 

[mawalters]

Do the math in the PLC. That works for me. I don't like having alot of thingsgoing on in the HMI that is on a Microsucks platform. You know where that is coming from.

I am trying to stay away from doing it in the PLC. For one thing there is alot more Data that I need to combine and calculate and they come from many different PLCs and I want to trend some of those new tags into a db file for future handeling.

The other reason I would prefer not to do it in the PLC is I dont learn anything new that way either.

The data is all there, its just in displays on the HMI instead of in tags, or even into variables woulf be nice.

Haven't quite had any luck with derived tags. Going to have to look and see if defined tags are different. I dont remember seeing anything called defined tags.