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Getting eronoeus readings on SCXI 1102
Joey Wood
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06-13-2001 02:55 PM
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I have a pci-mio-16e-1 daq board and a scxi 1001 chassis a scxi 1102 card and a tbx 1303terminal block. I am reading a temperature of 167 deg f with this system but it should be 202 according to 2 other calibrated instruments. What could be the problem?
BruceAmmons
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06-13-2001 11:23 PM
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Joey,
A few questions:
Are you using an example program to read the temperature? If you have written your own code, you could have a bug in it.
Are you using the correct cold junction for the terminal block? If you select the wrong cold junction, it will give you the wrong reference temperature. If the cold junction temperature isn't displayed, check it with a probe.
Are you using the right units? Conversions between deg C and deg F can get you every time.
Are you using the right thermocouple type?
This should get you started...
Bruce
A few questions:
Are you using an example program to read the temperature? If you have written your own code, you could have a bug in it.
Are you using the correct cold junction for the terminal block? If you select the wrong cold junction, it will give you the wrong reference temperature. If the cold junction temperature isn't displayed, check it with a probe.
Are you using the right units? Conversions between deg C and deg F can get you every time.
Are you using the right thermocouple type?
This should get you started...
Bruce
Bruce Ammons
Ammons Engineering
Ammons Engineering
06-14-2001 09:31 AM
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Joey,
Since you are posing the question in this group, we have to assume that you are using LV to do this.
Are you using the example VIs such as
found in the Help->Search Examples->Data Acquisition (DAQ)->SCXI->SCXI-1102/1127/1101 Thermocouple.vi. (Or if you have the same essential VIs).
If you haven't, take a look at that example.
I have essentially the same hardware as you describe, except I'm using a PXI-6052e (multi-IO).
Either way, there are a couple of things that you can check on.
As Bruce said, make sure that you select the correct TC type for the conversion.
If you wrote your own VI(s) are you adding the temperature reference??
The example shows how to do this.
(If you are using an external reference such as an ice bath th
ermocouple
[of the same type, of course] in the circuit, then that is taken care of.)
If you are using the CJC in the 1303, you have to set the CJC type to "Thermistor"
Make sure that you are reading the correct channel. eg the first channel is 0...
Make sure that you set the input range (gains) to the correct range.
If you wrote your own VIs from scratch, you may want to run the example VI that I
mentioned above, and see if you get the same results from that.
Dave
"Joey Wood" wrote in message news:50650000000800000013210000-991728092000@quiq.com...
> I have a pci-mio-16e-1 daq board and a scxi 1001 chassis a scxi 1102
> card and a tbx 1303terminal block. I am reading a temperature of 167
> deg f with this system but it should be 202 according to 2 other
> calibrated instruments. What could be the problem?
Since you are posing the question in this group, we have to assume that you are using LV to do this.
Are you using the example VIs such as
found in the Help->Search Examples->Data Acquisition (DAQ)->SCXI->SCXI-1102/1127/1101 Thermocouple.vi. (Or if you have the same essential VIs).
If you haven't, take a look at that example.
I have essentially the same hardware as you describe, except I'm using a PXI-6052e (multi-IO).
Either way, there are a couple of things that you can check on.
As Bruce said, make sure that you select the correct TC type for the conversion.
If you wrote your own VI(s) are you adding the temperature reference??
The example shows how to do this.
(If you are using an external reference such as an ice bath th
ermocouple
[of the same type, of course] in the circuit, then that is taken care of.)
If you are using the CJC in the 1303, you have to set the CJC type to "Thermistor"
Make sure that you are reading the correct channel. eg the first channel is 0...
Make sure that you set the input range (gains) to the correct range.
If you wrote your own VIs from scratch, you may want to run the example VI that I
mentioned above, and see if you get the same results from that.
Dave
"Joey Wood"
> I have a pci-mio-16e-1 daq board and a scxi 1001 chassis a scxi 1102
> card and a tbx 1303terminal block. I am reading a temperature of 167
> deg f with this system but it should be 202 according to 2 other
> calibrated instruments. What could be the problem?
econwendy
Member
11-03-2007 01:22 PM
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How do you go about obtaining a cold junction temperature? Is it necessary for the operation of the thermocouple?
