Need help incorporating the second counter into a current data acquisition routine (continuous retriggerable AI).

[DrObb]

My current application acquires data when it sees a TTL trigger line.  Then it wait until the next TTL pulse and continues taking data until the user stop the data acquisition process.  I use "counter 0" as counter source.  The program works well.  However I need to read digital data everytime I take AI data.  I plan to use "counter 1" to read the digital data.  The trick is that I need to synchronize both AI and counter 1 readings. Therefore the counter 2 will acquire data when AI acquires data.

Here is the code I implemented and would like to know if it is correct.  The new code (implementation of second counter) is in the bottom part of the code.  I will really appreciate your help. 

Yajai

[Sean_F]

Hi DrObb,

What is sounds like you want to do is to specify an external sample clock for your analog acquisition and a digital acquisition. Is there a reason in particular that you're using a counter? What hardware are you using? If you simply want to sample a digital and analog channel on the same clock edge, this won't be very difficult (provided your hardware supports hardware-timed digital IO). You can find an example of this being done in C by going to: 

Start » All Programs » National Instruments » NI-DAQ » Text-Based Code Support » ANSI C Examples and then navigating to  Synchronization\Multi-Function\ContAI-Read Dig Chan

Regards,

Sean