count rising edge specifier "10280" generates error "-200220"

[tyler22]

Hello,

I am using the USB-6008 with PFI 0 configured as an edge counter.  Everything works fine when I use it to count falling edges with the specifier "10171", but DAQmxBase Create Channel (CI-Count Edges).vi generates the error above if I simply replace "10171" with "10280".  Is this specifier not recognized by the device?

Thanks,

Tyler

[Matt_L]

Hi Tyler,

You're using the 6008 OEM correct?  Just wanted to make sure since the regular flavor doesn't appear to have PFI pins.

Which version of LabVIEW and DAQmx Base are you using?  I know that in the regular DAQmx, that CI-Count Edges task has a wire for edge type, and you should be able to right click->create constant as 'Rising' or 'Falling'.

[tyler22]

Hi Matt,

Yeah, it's the 6008 OEM (or whichever flavor has a PFI 0 pin).  My LabVIEW version is 12.0 Student Edition and I have the latest DAQmx Base version for Mac.  The problem persists whether I do the "create constant: rising" as you suggest, or manually enter the specifier for rising edge.  Both methods work for falling edges.

Maybe I should just mention what I'm doing and see if there's a simple workaround.  I have two limit switches (one for x and one for y on an x-y table) and I want to use the 6008's single counter to get edge signals from both switches.  So, my idea was to use a rising edge to signal x=0, followed by a falling edge to signal y=0.  But my counter can't seem to count rising edges...

Thanks,

Tyler 

[Matt_L · Accepted solution]

Hi Tyler,

I dug into this and did find an internal report, and apparently only a falling edge can be used as an edge trigger with counter tasks.  The other issue is that, even if you could use both, there is only one input pin to this counter and only one edge type can be detected at a time.  The only workaround I can see would be to try to find a device with more counters, or grab another 6008 and use it to count the edges from the second switch.

[tyler22]

Hi Matt,

Thanks for looking into this, and giving those suggestions.

Tyler