synchronization of two DAQ 6218 M-series

[L.Boehm]

Hi everyone,

I am trying to synchronize two DAQ 6218 units but I keep getting the error 89136, stating that I am using the wrong routing. I have been looking at a lot of posts and I have not been able to find one that explains how to do the physical linking of the two devices - at least not so a newbie like myself could understand it 🙂

I have tried to look at NI_max to see the possible routing, but it did not make a lot of sense to me. On my device I can not find any I/O's named PFI, but i devided to use P out of device #1 and P in on device #2.

I have attached a picture of the VI, the ni_max interface and one of the physical setup.

I hope that someone out there can help me, thanks ! 🙂

[JakeA]

Hi L Boehm,

I believe that if you have a look in the specifications document for the 6218 (http://www.ni.com/pdf/manuals/375199b.pdf, pages 7 and 😎 then it details which of the DIO lines are also usable as PFI lines and their potential uses. Onc eyou get the PFI lines connected up so that one 6218 can trigger the other then I think it should solve your problem. Let me know how it goes and whether you have further questions on this.

Best regards,

Jake Akhtar

[Alexander_Sobolev]

Can you post sync_daq.vi (in 2011), not picture?

What is that trigger setting VI in the second task? Why can not you use the same VIs as in the first task?

>> I have tried to look at NI_max to see the possible routing, but it did not make a lot of sense to me.

It makes sense. PFIs are connections available as screw terminals or BNC inputs, other are internal terminals. You can connect internal terminals to PFIs using DAQmx routing vi. To use internal terminal, you can type its name or Right click digital terminal -> I/O name filtering -> Show advanced terminals.

Correct link for the manual is http://www.ni.com/pdf/manuals/375199b.pdf No comma in the end.

On pages 14, 15 it shows board pinout and PFIs location - if you have custom labels, you can identify terminal by location.

Note on sync_daq.vi. With continuous samples DAQmx read outputs number of points currently in the buffer. Without loop delay it tries to go at infinite rate, showing small number of points (or even 0)

Can you give more details on synchronization?

Should tasks acquire samples simultaneously (have common ai clock)? 

Does your start trigger arrive once or is it a periodic signal? In the second case your tasks can start not simultaneously (from different periods) and get out of sync. For ~1 ms syncing, put both start tasks into one frame of sequence structure. If triggers come more often, you may need to consider hardware syncing to ensure they trigger from the same edge.

[L.Boehm · Accepted solution]

Hi guys, I am sorry that I have not answered your answers which are much appreciated. 

I found that I had actaully just made a really rookie mistake. I had connected "out" to "out". 

Sorry to have wasted your time 😕

[JakeA]

No problem, thanks for letting us know. Best of luck with the rest of the project!

Best regards,