I am trying to configure Process timer Tag in PI server, but it is giving "illegal compression deviation defined" error when I save it, as i have kept blank zero and span field .
The difference between span and zero is used to calculate compdevpercent / compdev. Additionally zero and span come into play e.g. with ProcessBook trends when using "Database" to specify minimum (zero) and maximum(span - zero) for the y-axis.
When trending a timers values over time, we can expect a straight line with constant lead that resets from time to time. For this reason compdev / compdevpercent = 0 with compression enabled (compressing = 1) should be sufficient.
To summarize, unless you recognize any issues with e.g. visualization, the following settings should be sufficient:
compdevpercent = 0 (compdev = 0)
compressing = 1
zero = 0
span = 100
Do you see any issues with these settings?
without knowing what tool you've used to create the Point, it's difficult to be certain what has caused the error but I assume a divide by zero exception has been caught when calculating comdevpercent / comdev point attribute based on span and zero attribute values. It's also difficult to suggest settings without knowing what information the point is supposed to receive but I suggest setting zero = 0 and span = 100. If this doesn't work well or the value range is different, you can adjust these values at any time.
Thanks for reply Gregor.
I only want to show the value of timer in graphic, but i don't know what to give in span and zero as for timer tag there is no range as of i know.
I want to know how to Configure timer tag, Is it the same method as it is for analog Tag or is the other way around.
What is the unit reported by the timer tag? When does it usually reset? What is the data type you would like to use with the PI Point?
Your answers to these questions may help to provide you with a better suggestion than the one made before.
Have you tried zero = 0 and span = 100?
Thanks for Reply
The unit for Timer is MInute
It usually reset on some internal logic conditions.
data type is float32 on DCS side, so i will be using same.
And i have tried it with 0 as zero and span as 100 but since it is timer value, no range is defined on DCS side.
Thanks Gregor for Clarification regarding Span and Zero. I will check it.
I also want to ask regarding Performance equation.
What to keep data type of performance equation?
For e.g i want to configure one PE (if 32bl01.pv01=1 then AUT elseif 32bl01.pv02=1 then MAN else NO OUTPUT()).than what to keep data type of PE.
and Can i make text visible and transparent through PE.
Please consider creating a new question when you have a question that is on a different topic or after selecting a correct answer like you did within this thread.
Looks to me as if you like to create a calculated PI point that is supposed being serviced by PI Performance Equation scheduler. Values 'AUT' and 'MAN' look like Digital States. Hence the PE points type should be "Digital". Please make sure to have a Digital State set available that contain states 'AUT' and 'MAN' so you can assign the proper Digital State set (point attribute digitalset) when creating the point.
PI ProcessBook offers to control the color of certain controls / symbols based on a PI points value. Please look for Multi-State Symbol within the ProcessBook documentation. Please note that not all symbols are supported. Members of the group of supported types are PBValue, PBBarGraph and PBTextBox. Members of the unsupported symbols are e.g. PBTrend and PBImage.
Noted, i will take care from next time.
The point which i am going to use in performance equation that i have kept digital with respective digital states assigned.
But what to keep data type of PE Point that is my concern.
I am sorry but I don't understand your problem / question. Can you please elaborate about your concern a bit more detailed?
I am just asking when we create Performance Equation point, than what to keep the data type of Performance equation point.
The general answer to this question is, it depends on the equation. When e.g. counting events, the matching choice would be an Integer type. Because your calculated point is supposed to report states, point type Digital is the proper choice.
what i understand from it means that it totally depends on the output which we get from performance equation (i.e, suppose i want to show AUT and MAN from PE point than data type for that point should be "string")
that's one option but resource and performance wise not the best one. I suggest creating a Digital State set with the desired states (if not existent already) and to use point type Digital.
For detailed information, please refer to PI Data Archive System Management Guide -> Manage PI Points.
You can find learning videos at OSIsoft's Youtube Learning Channel for many PI related subjects. I haven't watched Create a PI Performance Equation Tag. v2010 but could imagine you find it useful.
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