CJC Configuration Using SCXI1102 and SCXI1303 on a SCXI2000 Chassis

[Sergio Perillo]

I am trying to read 10 J-Type Thermocouples using the configuration above and I am having problems to configurate the CJC builted-in the SXCI-1303 Terminal Block attached to the SCXI1102. I try to add a virtual channel but there is no "thermistor" opption available, but a series of thermocouple types, RTD, voltage, current, resistance, etc. I am running LV5.1
Do the system have to recognize the terminal block? On the SCXI1102 Properties folder I choosed the SCXI-1303 accessory and tryed to create a virtual channel. I am NOT using any LV VI so far, but tryng to read the CJC temperature by right-clicking on supposed virtual channel assigned as CJC and clicking "Test". The reading has absolutely no meaning s
howing 900C.

[Eric Meyer]

The SCXI-1102 does not require a separate virtual channel as you would need if using an SCB-68. The cold junction compensation is handled automatically for your virtual channel by the driver. Just add your 10 type J's and go!

The voltage output from the onboard temperature sensor is multiplexed, along with other signals from the SCXI module, to channel 0 on the DAQ device. If you really want to read this signal, use the LabVIEW channel string MTEMP.

The SCXI-1303 uses a thermistor to measure the temperature. To convert the voltage reading to a temperature, use a thermistor conversion formula.
In LabVIEW, use the Convert Thermistor VI.Refer to "Transducer Conversion Functions" in the NI-DAQ User Manual for PC Compatibles, for more information.

regards,
E
ric Meyer
National Instruments

[Dave_Karon]

I've been using "CJTEMP" for the CJC on my SCXI-1303
(PXI-6052E, PXI-1011, SCXI-1102, SCXI-1303, DAQ 6.8.1, LV5.1.1)

Can either MTEMP or CJTEMP be used?

Thanks
Dave Karon
Concepts NREC

[MickeyD]

Hi everyone,

To clear up the issue of the MTEMP or CJTEMP for the SCXI 1102 they are going to be the same.  The 1102 does not have a choice to access the channels in parallel.  When using the 1102 with DAQmx the channel you will want to add is "_cjTemp" This will show you the voltage being read from that thermistor.  If there are any other questions about this please let me know.

Thank you,

Michael D
Applications Engineering
National Instruments