Fourth Counter on PCI-6602 Causes DMA Conflict Error Message Hardware: Counter/Timers (TIO)>>Devices>>PCI-6602
Problem: I can use three counters correctly in any order, but as soon as I add my fourth counter I get a DMA conflict. What is the problem? Solution: The PCI-6602, like most of our E series boards, has only three DMA channels. This means that to successfully use more than three counters, each counter after the third must be setup to use interrupts. You can do this by using Set_DAQ_Device_Info DAQ function where you set your infoType to be the desired counter and in the infoValue to be ND_INTERRUPTS. The documentation for the Set_DAQ_Device_Info function is under Start » Programs » National Instruments » NI-DAQ » NI-DAQ Help . In LabVIEW you should use the Set DAQ Device Information.vi. NOTE:The DMA conflict error only applies to older versions of NI-DAQ. The current version of NI-DAQ, version 6.9.3, has an automatic default transfer mode setting that uses interrupts if DMA channels are not available. Therefore, each counter used after the third DOES NOT need to be setup to use interrupts. If you need three, specific counters to use DMA channels, you can still make the above software calls and set counters to use DMA channels. The additional counters will automatically use interrupts and you will not receive a DMA conflict error. Related Links: 6601/6602 User Manual NI-DAQ Version 6.9.3 Download Attachments:
Report Date: 12/14/2000 Last Updated: 10/31/2002 Document ID: 24DFPLQ1 |
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