Output TTL Signal based on Analog Input

[FeisSSS]

Hi everyone,

I'm working on a task using cDAQ-9174 chassis to receive Analog input with NI9215 (pulsatile pressure measurement from a sensor) and use Labview to process it to output TTL triggering signal (Digital) with NI9402 to control event of another device. The process is real-time and continuous. From my initial search, analog level triggering (with one threshold) seems to be something I should look into, but I'm quite confused on how to configure the input and output signal using the two modules. 

Does anyone have examples to guide me how to start with this projects? Any hint will be appreciated!

Fei

[Henrik_Volkers]

If a simple threshold trigger works fine, I recommend an analog solution ... since no (sub)ns speed seems to be needed

a TL712  an simply control the trigger enable by software?

[FeisSSS]

Hi Henrik,

Thanks for your reply.

Could you be more specific regarding your comment on "analog solution"?

I tried to use the DAQmx trigger VI (Analog Edge) on a Simulated Sine Waveform Input to create the triggering TTL signal.  However, the attached error message shows that I'm using a wrong analog triggering source.