Use input digital edge to trigger the start of an output in another task with DAQmx USB-6210

[FilipN]

Hi,

I'm having trouble getting DAQmx Start triggering to work. Basically I 'd like to use an digital edge from counter 0 internal output (already exported to a pin) to trigger the start of counter 1 input. (And then use the start trigger again with the counter 1 internal output to trigger something else, as required by the subsequent tasks.)

But whether I use "DAQmx trigger - start trigger " or "DAQmx trigger property node - start trigger", it always returns me error 200452 "Specified property is not supported by the device or is not applicable to the task." at the trigger. But yet it is listed that NI USB-6210 does support start triggering. Anyone knows what's happening?

The screenshot of the part of vi is attached.

Thanks in advance,

[Kevin_Price · Accepted solution]

Counter *output* tasks can use the regular Start Trigger.  Counter *input* tasks need to use the more obscure "Arm Start" trigger.   You'll need to use a DAQmx Trigger property node to set this up, specifying trigger type (digital edge), signal souce / terminal, and polarity (rising / falling).  Here's a longer discussion and over here is an example.

This can be found in the docs, but it doesn't tend to jump out and wave its arms to announce itself as a special consideration for triggered counter measurements. 

-Kevin P

[FilipN]

Thank you Kevin,

It worked perfect now! It is really weird that this was never mentioned in the user manual or anything... But thank you!

[FilipN]

Hello again,

Sorry for another question, but this time I'm trying to use the start edge of a counter input to trigger a digital output, but neither start trigger or Arm Start trigger works. Any idea why this is happening?

I'm also struggling to extract the start edge of counter input to be used as a trigger (for the digital output), because there seems not an option to show that control signal. Any advice would be much appreciated!

Thanks

[Kevin_Price]

It'd be easier to help if  you posted your code.

Any pin that a counter input task can get a signal from should have a 'PFI' designation at the terminal block.  The digital task should then be able to configure to use that same PFI pin as its Start Trigger.  ("Arm Start" is *only* for counter tasks, the digital task would use the normal Start Trigger.)

-Kevin P