TClk with 6542 simultaneous gen and acquisition sessions

[billmileski]

Hello,

I am having a problem getting three sessions to be synchronized with TClk.

Labview 8.2.1

PXI-6542 (digital pattern generator and acquisition, HSDIO)

PXI-5122 (high speed digitizer, NI-SCOPE)

I want to precisely synchronize the three following:

- start of digital pattern generation (6542)

- start of digital acquisition (6542)

- start of high speed analog acquisition (5122)

I am sending a software start trigger to the 6542 pattern generation to get them all going.

I assumed I should gather session references for all three sessions above, provide them to TClk, configure homogenous triggering in TClk, and initiate TClk.  I have tried doing this but I get an error "duplicate session" for the 6542 acquisition session.  If I omit this session from the array going to TClk, the 6542 acquisition never triggers, and I get the following error:

"Specified operation is only supported while the session is running. Initiate the session before requesting the operation and make sure that the session has not been aborted." 

I'm not calling HSDIO Initiate for this session (nor any of them), so this makes sense, since the TClk Initiate call is not aware of this session? But calling Initiate would defeat the purpose of trying to use TClk?

Help!

Thank you,

Bill

[Raajit_Lall]

Bill,

It seems like you are trying to synchronize the acquisition and the generation on the HSDIO board and also trying to synchronize the digitizer at the same time.  You are right about wiring all three of the sessions into the NI-TClk Configure For Homogenous Triggers.vi.  You should wire only one of the HSDIO sessions.  If you look at the example Multi-Device Dynamic Generation and Acquisition-Source Synchronous (TClk).vi, you will notice that only the generation sessions use the TClk.  The acquisition session is still synchronized using the strobe and connecting PFI1 to PFI2.  I think this would be the best method for you to use as well.

Also notice that you are calling the initiate session for the acquisition session because you are not using TClk to synchronize it.  The other sessions that you are using are still initiated using TClk so you do not need to initiate those sessions.

Please keep in mind the external connections that you need to make to synchronize the acquisition and the generation on your HSDIO board.  According to the example :

IV I/O Connection Overview:
To ensure source synchronous, use equal length cable to make the following connections:
1) DDC CLK Out on generatoring devices to Strobe on acquiring devices.
2) PFI 1 on generating devices to PFI 2 on acquiring devices.
3) Data lines from generating devices to data lines on the acquiring devices.

Also, it seems like this thread is a continuation of this other thread. We can just continue on this thread itself.

Hope all of this helps.

Regards,

Message Edited by Raajit L on 05-29-2007 06:59 PM

[billmileski]

Raajit,

Thanks for the reply.

If I understand you correctly:

- I gather the HSDIO gen session and the NI-SCOPE acquisition session in an array and give to TClk, with homogenous triggering, and call TClk Initiate.

- I treat the HSDIO acquisition session separately, and call HSDIO Inititate on that session.

- I wire the 6542 DDC Clk out to Strobe (I have a 2162 digital accessory breakout box where I would do this).

- I wire the 6542 PFI1 to PFI2 (also at the 2162 breakout box).

Would I export the 6542 gen session start trigger to PFI1 and set up the 6542 acquisition session start trigger to use PFI2?

Are there any other properties for either 6542 session that I need to set?

Bill