Synchronise AI and DO tasks using Different Sample Rates on a 6132 and 6259

[ColinOfEd]

Hello,

I'm attempting to create a pulse-echo system using PCI-6132 and PCI-6259 cards.

I am generating a digital output on the 6259 and reading an analogue input on the 6132.

The pulse is being detected by the 6132 but there appears to be significant jitter. I have two questions regarding this:

1. Is it possible to synchronise these two cards given that I want a lower sample rate for the AI (6132) than the DO (6259)? I've seen several synchronisation examples but haven't come across this yet.
2. What is the best method of ensuring the AI and DO tasks start simultaneously?

I'm using LabView 8.6 with NI-DAQ 8.72.

Thanks for any help!

Colin

[Christian Mergl]

Hey,

1. Is it possible to synchronise these two cards given that I want a lower sample rate for the AI (6132) than the DO (6259)? I've seen several synchronisation examples but haven't come across this yet.

The best way to synchronize this cards is using an RTSI cable. Sure, you can use a lower Samplerate for AO then for the DO. If you look for one of the Multi-Device-Synchronization examples you will see that it's necessary to create a sample clock for the DO, which in your case could be the AI Sample Clock. So both would run with the same Sample Clock, but with different Sample Rates.

2. What is the best method of ensuring the AI and DO tasks start simultaneously?

Using the AI Start Trigger. You configure the DO task to start with the AI Start Trigger which comes up when the AI Task beginns to sample.

Hope this helps,

Christian

[ColinOfEd]

Hi Christian,

Thanks for your quick reply! I've had a look at the "Multi-Device Synch-Analog Input-Finite Acq-Analog Start" example and tried to adapt it for my purpose (please see attached file).

I don't have a RTSI cable at present but will get hold of one. I didn't understand using the same sample clock for both tasks however the example seemed to show a method of synchronising two sample clocks. I noticed that the DAQmx Timing property nodes are different for the M and S series devices - have I placed these correctly to set the S series 6132 (Dev2) as a master to the M series 6259 (Dev1)?

I'm very new to this so I appreciate your help

Thanks,

Colin