NI 9203 current input I/0 module

[jimf]

I'm looking at Fig. 3 Connection diagram on the NI 9203 and I don't understand what the Sensor is.  Usually to measure current I measure the voltage drop across a resistor and I need 2 isolated differential inputs for each current I'm trying to monitor.

How does the 9203 measure current?  I hope I'm not being too dense here but I just don't see it from the diagram.

Thanks,

Jim F.

[Ed W]

Hi Jim,

Thank you for posting to the NI forums.

The drawing in the 9203’s Operating Instructions shows the correct setup for measuring current on multiple sensors.  The method that you described for measuring current on a typical DAQ device is accurate.  However, because the 9203 is designed specifically to measure current, it converts the voltage measurement internally.  Rather than using a resistor in parallel with the portion of the circuit for which you’d like to measure current, the 9203 has internal resistances that are used.  The voltage measurement is taken across the internal resistances and then converted to a current using Ohm’s Law.

I hope this helps!  Please post back if you have any further questions.

Regards,

Ed W.

Applications Engineer

National Instruments