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tag update rate

HOW CAN FROM BLOCK PROGRAM IN LABVIEW 7.1 CHANGE DE TIME UPDATE OF ANY TAG.
 
OR ANY BODY HAVE AN IDEA ABOUT CHANGE THE RATE OF ACQUIRE DATA IN RUNTIME WORKING WITH DATASET.
 
THANKS,
ANDRES
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Message 1 of 17
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Hello,
 
I don't understand what you are asking.  Can you be more specific in explaining what you mean when you say, "CHANGE DE TIME UPDATE OF ANY TAG."  You also mention, "OR ANY BODY HAVE AN IDEA ABOUT CHANGE THE RATE OF ACQUIRE DATA" - what hardware are you using to acquire the data?
 
Looking forward to your repost!
 
Best Regards,
 
JLS
Best,
JLS
Sixclear
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Message 2 of 17
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These are the tag attributes that can be changed inside a vi in labview 7.0. I would set the tag update rates and the I/O group update rate to the shortest value ever required. Then control the read rate using the timeout/time interval input to the read tag.vi, read multiple tags.vi, or the trend tags.vi.
 
 
 
Message 3 of 17
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Hello,
 
I don't understand what you are asking.  Can you be more specific in explaining what you mean when you say, "CHANGE DE TIME UPDATE OF ANY TAG."  You also mention, "OR ANY BODY HAVE AN IDEA ABOUT CHANGE THE RATE OF ACQUIRE DATA" - what hardware are you using to acquire the data?
 
Looking forward to your repost!
 
Best Regards,
 
JLS
 
 
Hi,
i say "change time update of any tag" because i'm using opc to acquire the data but need change the time of sampling data.  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.
 
i'm using datasets to store and save the information.
 
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Message 4 of 17
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I don't think you can change the OPC update rate at run-time.  You can try changing the Update Deadband using the tag attribute from Unclebump's post.  But am not sure if this requires an Engine restart. 

Maybe what you could do is, to put the Read Tag VIs in different loops and then control the rate of these loops individually, and at run-time. 

-Khalid

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Message 5 of 17
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thanks for the responses,

in this application i don't use read tag.vi because i read the information store in citadel throug datasets (this is the best way to store/read relationship information)

the information is the result of test (measure temperature) then when start the register of the information until stop this register there are days or weeks.  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.

regards,

andres

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Message 6 of 17
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Hi Andres,
 
So, you basically want to log data (into DataSets) at different rates?  And want this logging-rate to be configurable at run-time? 
 
-Khalid
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Message 7 of 17
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I looked at datasets for an application of mine. I ended up converting my array of data into a binary string and writing it to a string memory tag. The entire array gets stored as a single datapoint for the string tag. It does require you to decode the string data when you read back history info.
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Message 8 of 17
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Hi Khalid,
 
yes!, i need do it to use the citadel database
 
Andres
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Message 9 of 17
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hi unclebump ,  i don't understand what is the gain of convert the data to a memory tag string.  this is how feedback the same information to the database?
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Message 10 of 17
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