Why Doesn't Count Direction Work Properly on the Bus-Powered USB M Series Devices?Hardware: Multifunction DAQ (MIO)>>Portable>>USB-6210, Multifunction DAQ (MIO)>>Portable>>USB-6211, Multifunction DAQ (MIO)>>Portable>>USB-6215
Problem: I am trying to program an event counting task in NI-DAQmx for my USB-621x device. I would like to use an external signal to control the count direction, but it doesn't work right when using the default counter terminals. Solution: Count direction is controlled by the CTR n AUX line. On some M Series devices, the CTR n AUX line is shared with the CTR n B line, so some references refer to using CTR n B to control the count direction. In the truest sense, the count direction is controlled by the CTR n AUX line, not the CTR n B line. This is especially important on devices like the USB-621x where CTR n AUX and CTR n B do not share the same physical pin. On the USB-621x, CTR n AUX shares the same pin as CTR n SRC. Because of this, you cannot use an external signal to control the count direction with the default counter terminals. You must explicity set the terminal of either CTR n SRC or CTR n AUX to a different physical pin using one of the following DAQmx properties: Related Links: Attachments:  - set_count_terms.JPG
Report Date: 11/22/2006 Last Updated: 11/30/2006 Document ID: 43LEFME1 |
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