Signal Conditioning

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Current measurement with SCXI 1102 and SCXI 1303

Hello

 

We are using a SCXI system to obtain temperature-, pressure-, and flow readings. The temperature data is obtained via thermocouples (voltage output) and the pressure- and flow transmitters output a 4-20mA signal. We have one SCXI 1102 module and a SCXI 1303 terminal block at our disposal. According to the forums below there are two ways to accommodate the current readings alongside the voltage readings in the same module. Both methods involve employing a high precision 249 Ohm shunt resistor, either inside the terminal block across the measuring terminals, or alternatively soldered onto the 1102 module itself at the appropriate channel location. From what I gather there is no real difference between the two methods, or am I missing something (except for the soldering method to be a somewhat more permanent configuration)?

 

http://forums.ni.com/t5/Multifunction-DAQ/Can-a-SCXI-1102B-with-a-1303-block-have-some-channels-read...

http://forums.ni.com/t5/Signal-Conditioning/1303-current-measurement-configuration/td-p/559740 (It refers to Appendix E of the SCXI 1102 user manual at some point)

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Hello,

 

Both methods are equivalent, at the end the only difference is the location of the precision resistance. If you reconfigure your system frequently I think the 1303 method will be more convenient. However, if this system is designated for this test I think that soldering the resistances to the 1102 will be the best

option.

 

SCXI Resistor Kit:

http://sine.ni.com/nips/cds/view/p/lang/en/nid/1644

 

Regards,

 

MCOTO

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