DAQmxCfgChangeDetectionTiming not allowed with NIPXI6542?

[scubasteve]

When running the NI sample program "Read Dig Chan-Change Detection Event" with my Ni PXI 6542, I get the error that the Property Sample Timing Type requested is not allowed, the requested type was DAQmxCfgChangeDetectionTiming , allowed types are ...SampleClk or ...OnDemand. Is this saying that the change detection functionality doesn't work with the NIPXI6542 or is there some other problem?

[scubasteve]

OK, never mind. I finally found the "not supported" list.

[DJ_L.]

Hey scubasteve,

I was just curious as to why you are using the DAQmx functions and not the niHSDIO functions with your PXI-6542? Are you able to find the HSDIO example programs? Let me know if you have any further questions or concerns. Thanks, and have a great day.

Regards,

DJ L.

[scubasteve]

I need functionality to monitor the state of a pin and perform some action or generate an interrupt if the state changes. HSDIO doesn't seem to offer that (other than hooking up a trigger line to the pin I'm monitoring and initiating a hardware generation on a state change. I couldn't find any examples in the HSDIO samples demonstrating that functionality.

It's a fairly common function for a Digital I/O device and since th 6542 shows up in MAX as a QAQmx device, I thought that was how it was implemented. Guess not.

[DJ_L.]

Hey scubasteve,

HSDIO actually does offer a somewhat similar functionality to what you are looking for in the Hardware Pattern Match. First, to find the HSDIO example programs, you can do a search on you machine for "niHSDIO", and there should be a folder with examples in it similar to this following directory: C:\Program Files\IVI\Drivers\niHSDIO\Examples. In there you should find Dynamic Acq, Gen, Acq & Gen, and some others. If you go into the Acquisition folder there will be a bunch of examples including one called DynamicAcquisitionHardwarePatternMatch. This might be what you are looking for. You will probably have to make some changes to the example for what you want, such as looking for a pattern on only one of the data lines, and you can run it up to perform a reference trigger or event. Also, you can set up the digital pattern match to trigger based on the following:

• X: ignore the physical channel
• 0: Match on a logic low level on the physical channel
• 1: Match on a logic high level on the physical channel
• R: Match on rising edge on the physical channel
• E: Match on either rising or falling edge on the physical channel
• F: Match on falling edge on the physical channel

You can check out more details of the pattern match functionality in the NI Digital Waveform Generator/Analyzer Help file. Please let me know if you are still unable to find the HSDIO examples, or if you have any further questions or concerns. Thanks, and have a great day.

Regards,

DJ L.