High speed Temp logging using TC08(USB) via LabVieW 8.2

 
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vavoul
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Joined: 24 Mar 2008
Posts: 1

PostPosted: Mon Mar 24, 2008 10:12 pm    Post subject: High speed Temp logging using TC08(USB) via LabVieW 8.2 Reply with quote
Dear All,

I am trying to write a vi for a TC08(USB) that will enable me to acquire K thermocouple data at ~high speed over 30 Hz per channel. The Usage of labview is mandatory since I have to integrate (synchronized) this vi with other DAQ and DMM measurements.

From manual I understand that in order to succeed high data logging rates the streaming mode should be selected via the use of usb_tc08_run and usb_tc08_get_temp commands. Unfortunately, all my efforts are unsuccesfull and I desparately want help. Smile

Using Get Single mode, I managed to prepare a vi tha suits my application logic perfectly but the acquisition rate is too slow only 4 Hz (even for two channels). ( I attach the vi: USB_TC-08_Single_82_2channels_4Hertz.vi)

Additionally I attach the outcome of my efforts for streaming mode. I tried to keep same logic since this suits my experimental plan, but when I start the vi, LABVIEW closes....with the standard message :"LabVIEW 8.2 Development System has encountered a problem and needs to close. We are sorry for the inconvenience."

Thank you in advance,

Antonios

USB_TC-08_Single_82_2channels_streaming.vi
 Description:
effort for streaming mode

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 Filename:  USB_TC-08_Single_82_2channels_streaming.vi
 Filesize:  22.96 KB
 Downloaded:  45 Time(s)
USB_TC-08_Single_82_2channels_4Hertz.vi
 Description:
succesfull effort for singe get mode

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 Filename:  USB_TC-08_Single_82_2channels_4Hertz.vi
 Filesize:  90.76 KB
 Downloaded:  57 Time(s)
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gruntman
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Joined: 28 Sep 2006
Posts: 87
Location: Garden City, KS USA
PostPosted: Mon Mar 24, 2008 10:41 pm    Post subject: Reply with quote
Antonios,

The TC-08 has a conversion time of ~100ms per channel. Therefore even if only one channel was enabled you will be able to only collect data at approximately 10Hz under ideal conditions, nowhere near your desired 30Hz.

I briefly looked at your streaming example and noticed one major flaw. You are calling usb_tc08_legacy_get_temp when you should be calling usb_tc08_get_temp. The legacy method only works if you set the TC-08 up into legacy mode which you do not need to do.

Regards,

Richard Boyd
Crag Technologies, Inc
http://www.pc-oscilloscopes.com
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