Inaccurate Read from Voltage Generated by SCXI-1581 Hardware: SCXI>>Modules>>SCXI-1581
Problem: I am using a SCXI-1581 to generate a current output. To verify it is working correctly, I placed a resistor across the EX0+ / EX0- terminals to read the voltage. The voltage I am reading across the resistor is incorrect. What am I doing wrong? Solution: The SCXI-1581 delivers 100 uA into any load from 0 Ohm to 100 kOhm. You can use the analog-input channels of an E Series DAQ device to verify the current source generated from the SCXI-1581. Using an SCXI-1180 or the 50-pin breakout connector, you can route the signals to the analog input channel(s) of the DAQ device. If the E Series DAQ device is directly cabled to the SCXI-1581 in a single-chassis system, the DAQ device has channels 1 through 7 available to measure unconditioned signals. If you connect the signal to channel 0, you will receive an incorrect reading. If you continue to experience problems with the input signal, you can test the current output of the module. First, disconnect all loads from the channel you are testing. Second, measure the current-output value using an ammeter. If the ammeter has a fuse, ensure that the fuse is not blown before performing the measurement. Alternatively, place a known resistance R (<100 kO) across the current output and use a voltmeter to measure the voltage drop across it. If the current output is working, you should measure V = (100 × 10–6 A) × R, where R is given in Ohms. Related Links: Product Manuals: SCXI-1581 User Manual (March 2003) KnowledgeBase 2TGFDIRT : How Do I Use an SCXI-1102 in Conjunction With an SCXI-1581 Module? KnowledgeBase 3MNCHDUM : Can I Change the Output of the Current Excitation from the SCXI-1581 to be Less than 100uA in Hardware or Software? Attachments:
Report Date: 04/07/2006 Last Updated: 04/21/2006 Document ID: 3W6BKTQP |
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