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dt8837 Additional questions about continuous measurements


idsnt3
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Since there was no answer to the added question, I am posting a new post.

Tested by limiting RequestedScanIndex to 0~2097152 as shown in the attached file.

In this case, no error occurs, but the scan value is not output from the fetch function after one cycle.

How do I modify it to take continuous measurements?

Or is there no example where I can measure more than 24 hours at 25600 sampling? C++, C#, labview, whatever.

AnalogInTachCounterStreaming_MOD_2.vi

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Hello @idsnt3.

There is no canned example for the DT8837, which will allow the device to acquire data for more than 24 hours.  The RequestedScanIndex range is 0 to 2097152/number of channels.  When the Scan Index hits the top of the range, it is supposed to rollover to '0', but as you experienced, it does not.  As a workaround, what you could do is allow the RequestedScanIndex to reach a desired count and then in a loop, call Abort followed by Arm and Initiate, before calling GetStatus and Fetch.  The time it takes to abort and then fetch new data may be less than a 3 second gap. 

Regards,

Fausto

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Posted (edited)

Thanks for the reply.

In order to solve the problem, the method you mentioned has already been applied to the system.

Measuring is stopped and restarted twice in the early morning when the machine to be measured is not running.

Confirmed that it works well for 10 days. (25600 sampling)

However, in the case of other measuring systems to be applied in the future, 

this problem must be solved because the operation is carried out 24 hours a day.

 

I have one more question. The QuickDAQ program provided by dt8837 has the same problem.

As shown in the attached picture, if Enable Continuous Acquisition is turned off and Duration is set to 2day,

it is automatically set to 11:39:03 (hh:mm:ss). (51200 sampling)

If turn on the option and proceed with measurement, the measurement graph screen stops when the scan index becomes 2147450880.

I'm guessing the cause of the freeze in QuickDAQ is the same as what I asked.

Is it possible to fix the problem by modifying the windows driver of DT8837?

 

QuickDAQ_Enable_Continuous_Acquisition.PNG

QuickDAQ_Disable_Continuous_Acquisition.PNG

Edited by idsnt3
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Hello @idsnt3.

The DT8837 IVI-COM driver is only a 32-bit driver, which is why QuickDAQ and the IVI examples (including the VI examples) stop capturing data during your long term tests.  There is no plan to release a 64-bit IVI-COM driver for the DT8837.

Try using the SCPI example found in the following directory.
'C:\Program Files (x86)\Data Translation\Instruments\DT8837\SCPI Support\Examples'

image.png


Regards,
Fausto

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