10-19-2016 01:51 PM
I can create a RT timed loop timing source using the Digital Change Detection flavor of the DAQmx Create Timing Source.vi. This works well, but I cannot use the same port line to detect the polarity of the input when i wire the line into both the rising edge and falling edge inputs. To detect the polarity, I have to use a DI task on another coupled line input.
I would like to use the "Signal from task" flavor, but it doesn't seem to function with LabView RT (2015) and my PXI-6281 cards. Does anyone know how to get it to work or why it doesn't work?
There was a discussion about this years ago here but no indication of why "Signal from task" doesn't work on M-Series boards which support change detection like my 6281s.
Thanks,
XL600
10-20-2016 06:11 PM
Hi xl600,
Could you tell us a bit more about how the "Signal From Task" instance of the VI doesn't work? Does it hang, throw an error, etc? Also, if you could post some snippets, that would be helpful. We might be able to replicate it, or better see what it is you're doing that way.
10-20-2016 07:45 PM
Best would be to attach the entire VI that you are trying to run, attaching it as a .VI (not a picture, please).
Bob Schor
10-20-2016 10:01 PM
I'll try to come up with an example. The system is too complex to post the vi directly so I'll have to try it in a standalone vi.
10-24-2016 06:00 PM
Here's a demonstration.
To test, I externally tie PFI7 (ACQ_TRIG_OUT) to port0 line 6 (Sense) and port0 line 7 (Detect). Then drive PFI7 via MAX in single sample on demand mode.
The first VI uses two tasks
The second VI attempts to use a single Signal from Task timing source on either the sense or detect channel (Detect channel is shown wired). According to NI, Signal from Task auto-starts the task which is why I don't include the Start Task VI.
Thanks for taking a look!
XL600