software triggering

[bluebird72]

How to do software triggering for a Ni 9234 module?  

[Cy_Rybicki]

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019TmuSAE&l=en-US

Searching "DAQmx Software Trigger" in Google or NI Forums will show additional examples.

[Gregory]

There is a deprecated "Send Software Trigger" function, I'm not sure if it is supported by your module. The example Cy_Rybicki linked to actually waits for a hardware input to go high before reading from the module, using software to link the two hardwares together. Is that what you want, or can you explain your problem in more detail?

[bluebird72]

I am using NI DAQ system consisting from  NI 9234 with cDAQ-9174. My application is to measure the acoustic signal reflected from concrete deck. My NI DAQ does not have a hardware triggering. I need to use software triggering to trigger the acquisition of the input signal only when it is available. Please refer to the attached block diagram.

[Gregory]

The data acquisition system does not know when you are interested in the signal. It is your job as the programmer to either collect data right as you apply your stimulus, or to continuously collect data and then later pick out the part you are interested in. 

How do you apply your stimulus? If you do it with hardware connected to the computer maybe you can start collecting just before applying it, using the error wire to enforce the order that VIs execute.

[bluebird72]

Hi Gregory,

    Thanks for your reply. I understand the required task which is collecting data right as the stimulus is applied, the stimulus is an impact generated by a hammer. That's why I need to use software triggering to start data processing once the impact is applied

[Gregory]

You can use the DAQmx Start Task VI to tell your hardware when to start acquiring data.