National Instruments SCXI-1129 User Manual page 70

Common Questions
© National Instruments Corporation
This appendix addresses common questions you may have while using
your SCXI-1129 module.
How fast can I scan with the SCXI-1129 module?
The fastest scan rate for the SCXI-1129 is 125 scans/s. Typically,
when using a DMM to make accurate measurements, the DMM requires
hundreds of milliseconds. Consequently, the DMM becomes the limiting
factor in determining the scan rate.
What should I do if the software detects the module, but the switches
do not switch?
• Verify that the switches do not switch. Close your application program
and then launch the soft front panel as described in the Set up and Test
document you received with your kit. The soft front panel shows the
state of each relay switch on the module. Try closing and opening the
switches using the low level switch functions.
• Check the return codes of the NI-SWITCH operation to ensure that
there are no errors (negative values) or warnings (positive values).
You can also use the NI-Spy utility, which is installed with
NI-SWITCH, to check for error codes.
• Finally, verify that your program is correct. For reference, see the
examples described in the NI-SWITCH Software User Manual. The
NI-SWITCH driver also ships with several examples in source code.
Compare your algorithm to the ones in the examples.
What should I do if scanning does not work in the handshaking mode
with a third-party DMM?
• Ensure that you have configured the SCXI-1129 and the instrument to
correctly route all the trigger lines. The output trigger of the instrument
should connect to the trigger input of the SCXI-1129. In addition,
make sure the scanner advanced trigger of the SCXI-1129 connects to
the input trigger of the instrument.
• If you use the SCXI-1129 to initiate the scan, make sure the DMM is
waiting for a trigger before enabling scanning on the SCXI-1129.
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SCXI-1129 User Manual