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TC-08 & PicoLog recording @ < 1 sec

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TC-08 & PicoLog recording @ < 1 sec

Postby JAdamson » Fri Feb 04, 2005 6:56 pm

Using a TC-08 logger, PicoLog 5.10.3 and attached type-T exposed junction thermocouples, I have attemped to take temperature readings at intervals of 1 ms and 10 ms for 5 seconds. The TC-08 is attached to a desktop using a general, store-bought Serial-to-USB connector. I have an application that requires many quick readings in around 2-3 seconds.

However, the results in PicoLog show that most of the temperatures recorded are the same. For blocks of 1/2 to 1 second the readings are the same. Because I have a TC-08 I can only use the "Real-time continuous" recording method and not the "Fast block (single converter only)." I have set the "Readings per sample" to both 'As many as possible' and 'Single' without a change.

I am wondering why this is occurring since the data logger help says it should be able to read at the millisecond level. Browsing the forum, I ran across a reference to the logger using the Windows clock. Could this be a problem? Also, what about averaging of the incoming signals? The help files mention it. Is there a way to disable this function in order to gain a much quicker (albeit possibly skewed) reading?
JAdamson
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Postby Sarah » Mon Feb 07, 2005 10:24 am

Hi

Thank you for your post.

How many channels do you have active on the logger? The Serial TC-08 takes 200ms to take each sample and 200ms for the CJC, therefore if you are using a number of channels the sampling rate will be slower.

In order to prevent the unit averaging readings you use the "Single" sampling method as opposed to "As Many as Possible".

I would suggest that the reason you readings are not changing so quick is down to the sampling rate of the TC-08. Our new USB TC-08 is capable of sampling twice as fast and thus takes 100ms to take a sample. This may be of some interest to you.

Hope this helps

Best Regards
Sarah
 

Postby JAdamson » Mon Feb 07, 2005 2:31 pm

Thanks for the quick reply. You say the TC-08 takes 200ms to take the sample and 200ms for the CJC. What is the CJC? Does it stand for Cold Junction Conversion to temperature? So there's really nothing I can do to speed up the reading of results?

Thanks.
Josh Adamson
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Postby Sarah » Tue Feb 08, 2005 10:18 am

Hi Josh

Thank you for your post.

Yes, CJC stands for Cold Junction Compensation. Whenever it takes the temperature of the Cold Junction this also takes 200ms to sample - the same as sampling any other channel. It does not take a CJC readings for every channel's reading but more intermittently.

Unfortunately there is no way to speed up the process as it is due to hardware limitations rather than software ones.

Hope this helps

Best Regards
Sarah
 


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