CDAQ 9174 - Synchronization of Analog IPs and Digital OPs

[BrenS]

Hi everybody,

We're using a compact DAQ (NI 9174) to acquire analog IPs (using module NI-9205) while at the same setting digital OPs (using 2x NI-9401). The digital signals control LEDs and the analog signals are reading photo sensors. We wish to start reading the photo sensors before we start the LEDs. The LEDs changes pattern while the photo sensors are been read.

We can start the photo sensors before the LEDs but find that the start time of the LEDs with respect to the start time of the reading of the photo sensors vary from run to run. What we wish to do is synchronize the action of the analog IPs and the digital OPs so that this is consistent.

Is there a way to synchronize the analog IPs & digital OPs to a "master clock" so that we can lock the time between start read of photo sensors and setting the LEDs and make it fixed?

Hope this makes sense..

Any ideas?

Many Thanks!

[ikaiser · Accepted solution]

Hi BJ_phy!

I think the first two of these articles should answer your question:

• Synchronize Continuous Analog Input/Ouput with DAQmx Base
• How to sync and/or trigger NI-DAQmx devices in LabView
• Timing and Synchronization Features of NI-DAQmx
• Acquisition with Analog Triggering on a CompactDAQ

If this does not fir your question, could you please give a bit more information on what you are doing in your code? Are you just acquiring once or continuously, how have you set up the timing, are you using triggers, how are your DAQ tasks set up etc. Without knowing this it is quite hard to point you into the right direction.

Maybe share your code, if possible.

[BrenS]

Hi ikaiser,

Thanks for sending on the info, it was useful to understand whats going on. We ended up finding an example (very similar to that illustrated in your 3rd link) that works. When its documented we can share it in a follow up post - might be useful to others 🙂

Cheers,

B