tag update rate

[Donald]

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andress wrote:

… if i have data every 2ms (default) are a big amount of data unnecessary for temperature measurement for example, but excelent for other magnitud measure. i want change this rate in execution time in front panel. ...

… if i know that the test is for one hour can set the update time every 60 seconds, for example. but what happen if the test is for weeks and many times in the month, i think (i'm not sure) that slowly the citadel database and my application, for this reason i need change the time of update/save information in citadel. the only way that i find is changing the update time in the tags of my dataset. ...

yes!, i need do it to use the citadel database

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Andres,

What is the "update time" you refer when you say that "the only way that i find is changing the update time in the tags of my dataset"? The update rate in an IO Group configuration? The "Maximum time between logs" parameter in the overall historical logging configuration? Something else?

Logging data to Citadel is event-based rather than time-based; a good description of what that means was written by Jochen here.
Logging data to Citadel is also independent of the OPC update rate and IO Group update rate … unless there has been a poor choice in the value of the logging deadband or "Maximum time between logs" value … and maybe a few other things.

Are you getting unchanging temperature data logged to Citadel every "2ms"? … 200ms?
Do you have some tags that will need frequent logging and others that don't?

[Khalid]

You could use the "Log Deadband" tag attribute and change this at run-time. 

-Khalid

[andress]

Hi Donald,

yes, update time is the same update rate in an IO Group configuration.

i understand you about of the logging data to citadel in event-based mode using the deadband.  i could use the "Log Deadband" tag attribute and change this at run-time (how say Khalid above) and work fine. 

the problem is when try to register more than one tag, then every tag have a timestamp different because the value of every tag don't change to the same time, and for example i would have 10 values for tag1 and 20 values for tag2. how can make a history table of this two tags and only one timestamp?. 

i put log deadband to 0.00% and think make the citadel time-based using the update rate.  but i need it at run time.

thanks a lot.

[Donald]

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@andress wrote:

.... how can make a history table of this two tags and only one timestamp?. 

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Hi Andres,

You could make use of Decimate Traces.

[andress]

yes, i could do it, but then can or can't change the update rate in an IO Group configuration at run-time?

[Donald]

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@andress wrote:

... yes, i could do it, but then can or can't change the update rate in an IO Group configuration at run-time?

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Hi Andres,

A longer post from me will have to wait a few hours, but I'm pretty sure you can't change the IO Group update time during run-time in LVDSC v7.1.   It's a static property (meaning it can't be changed) in DSCv6.1 which I have.

[unclebump]

Hi Andress,

Look at the examples I posted in this thread for how I used memory string tags. I save cluster information as a packet into a string memory tag.

http://forums.ni.com/ni/board/message?board.id=170&message.id=139934&query.id=3099#M139934