Synchronizing 1 PCI 6220 and 2 PXI 6711 Boards

[EESteve1992]

Hello,

I have created a program that writes both digital signals to the PCI 6220 board and analog functions to two 6711 boards.  Upon testing the output of these boards on the oscilloscope, I discovered that the timing of the digital board was about a half of a second behind the timing of the analog board.  If anyone has any ideas about why this may be happeneing itd be greatly appreciated.  I believe it is a synchronization mistake.  I have the boards connected with an RTSI cable but i never reference the cable in the program.

[mikeporter]

Do you really have a PCI 6220 and 2 PXI 6711's.

How are you interconnecting the PC card with the cards in the PXI chassis? What is the source of the synchronization you are wanting to use?

Mike...

[EESteve1992]

That's my mistake, I just looked at the board and saw they are both PCI 6711, and all three boards are connected with an RTSI cable.  I was hoping to use one of the RTSI lines available on each of the boards for synchronization.

[mikeporter]

Under DAQmx Advanced functions there is a VI called DAQmx Connect Terminals.vi that allows you to internally connect various signals to the RTSI bus (among other locations). This will connect your cards to the RTSI signals.

What is the source of the synchronization signal?

Mike...

[EESteve1992]

I was hoping to connect the RTSI line to one of the 32 bit counters available on the boards.  Currently my program uses three independent counters for output.  However when I try to define a constant on the source node of the Daqmx connect terminal vi, it will only allow me to pick from RTSI lines and the reference clocks, no counters are available.    

[mikeporter]

One solution would be to run a wire (a real one! you know with copper inside it? ) from the counter output to one of the PFI lines on the same card and then tie the PFI line to RTSI bus...

There might be a more elegant way of doing it that someone could share, but this would certainly work. Just make sure that you document in your code the assumption that this jumper wire is in place.

Mike...

[EESteve1992]

So, if I run a counter to a PFI input line can I reference that same line for the clocking of the three program pieces?  just to make sure i only need to run the one physical wire from the counter output to the PFI inpur right?

[mikeporter]

Yes, because what you will do is use the VI I mentioned before to route the PFI signal to a line on the RTSI bus.

You then configure your other boards to trigger from the same line on the RTSI bus.

What will happen is when the counter goes off, it will cause the PFI line to change state. This state change is in turn passed to the RTSI trigger line you selected where it is applied in parallel to all the boards that you have configured to trigger from it.

Mike...

[EESteve1992]

I made the physical connection, but i'm not quite sure where the connect terminal vi comes into play with the clocking and channels. Any suggestions for things to change in my program?

[EESteve1992]

sorry that one might not be updated with the connect terminal vi