XNET: does setting MasterTimebase for a session set MasterTimebase for all sessions on a card/port?

[Matt_AM]

Greetings Fancy Folk,

Background:

I am running a test where I have 4 stations, each station having a PXI 8512/2 card.  Each station communicates to 2 device via XNET single point write and XNET XY read (one device per XNET port).  I am displaying my XNET read data and an analog in read data to a FP XY graph. 

Issue:

When I start my stations up, the XY graph looks like all the data is lining up well.  However, after a week or so, the data seems to be coming back to me as expected but there is a time shift between the XNET Reads and analog in data.  The data is still coming to me as expected, but now my XY timestamps are a second or so apart.  I believe that it has to be an issue with the MasterTimebase.  My plan is to set the MasterTimebase to PXI10 for the XNET cards and analog in card. However, I am not sure if setting the MasterTimebase to the PXI10 line for one session will set the MasterTimebase for all sessions on that port or all sessions on that card or just that session alone.  My assumption is setting the MasterTimebase for a session will set the MasterTimebase for the entire card. 

Additional info with XY graph not "lining up"

I know I am not in sync with everything and I figured that since its an XY graph, it wouldnt matter to much.  The graph is just a visualization of my data for the user and I'm not using it to determine any logic for the actual test.  To give a rough idea of what my graph looks like at start, think of 3 sine waves that are +/- 3 degrees out of phase.  I am interested that sine waves are all at the same period, all reaching the same amplitude, and all follow each other.  Their timestamps are closely align but aren't "dead on", and that's okay for this test.  After a week or so of testing, these sine waves are still +/- 3 degrees out of phase, but the timestamps are a second or so off.  I know my test is still running as I expect via visually verifying it.  I can try and make a quick visual of the graph if it's unclear what I am seeing.

Thanks,

Matt AM

[Matt_AM]

Fancy Folk,

It seems like you only have to set the MasterTimebase for one session on the port for the timebase to affect everything on the port (which makes sense).  It also seems like I have to set the master timebase for each port during initialization. 

I think I solved my problem of syncing my analog in with both XY reads.  I ended up putting the mastertime base for my analog in task (20Mhz clock on a 6052E) to PXI trigger7 vai DAQmx Connect Terminal.  I then used an XNET Connect Terminal to link the mastertimebase to PXI Trigger 7. 

I read that the trigger shouldn't be used for clocking, since there can be some issues with the trigger lines gating the clock twice.  I wasn't sure if the PXI 6052E or PXI 8512/2 have access to the PXI Star (backplane pin that should be for clocking based on what I read).  I'm hoping that my PXI trigger 7 clock will work fine.  I'll update if there's any issues.

Matt