Synchronize PXI-6542 and PXI-6511

[lmd2]

I am using a modified (PXI-6542) example to output a set of signals (20MHz) on several channels, and reading a set of DIO channels back on the same PXI-6542 module. I need to simultaneously read a few additional channels on a PXI-6511 (the discrete flags are not using as fast of a clock, but I need to correlate the two sets of signals. If anyone can point me to a sample that could get me started I would be very grateful.
(Using LabVIEW 7.1.1 on Win XP Pro)

[kalyanramuv]

Hello,

Can you be more specific as what level of synchronization you are looking for? PXI-6511 is a software timed digital acquisition device. In other words, you can't supply an external sample clock for PXI-6511. Usually, synchronization involves two devices sharing same clock or same trigger (so that they can acquire and start at the same time). You cannot synchronize PXI-6542 and 6511 to clock level. You need a board which has sample clock.

One solution, if you are not looking for faster rates on the extra channels, you can buy a Digital I/O which can phase-lock to the 10MHz backplane and start digital acquisition at the same time as the PXI-6542. The sample rate on 6542 can be configured to integer multiple of the digital I/O card to easily correlate the data.

You can also buy another 6542 and synchronize two 6542's.

Thanks,

Kalyan

[lmd2]

I am presently outputting the clock of the 6542 generation session to PFI 1, which is hardwired to PFI 3 (configured for the acquisition session trigger) in the breakout box. For what I am presently doing it should be sufficient to trigger the 6511 off the same trigger PFI 3; however there is a second phase to this project which I am not familiar with yet, and may require actual clock synchronization. I am going to determine the needs of phase 2 before going any further.
thanx for the help.

[lmd2]

can you point me to an example using the 6511? does it take an external trigger?

[lmd2]

Good Morning
I have been looking at examples, and came up with an idea which seems too good to be true, could you please tell me if this is do-able?
I am looking at the DAQmx example: "Read Dig Chan-Change Detection.vi"
Let us say I need to monitor six digital lines; if I setup the vi to read seven channels, with the seventh being the PFI 2 (some clock at a slower multiple of the 20Mhz) do a rising edge change detection on line 7, and have both clocks initially trigger together I could correlate the data? If this could work, what kind of sampling rate would I be able to achieve?

[JordanRandall]

Hi,

The example you are referring to is a feasible solution to a degree. It seems as though you are trying to make the tortoise as fast as the hair. The PCI 6511 does support change detection; however, the maximum rate of change detection is determined by the software response time, which varies from system to system.

 

Feel free to post a reply if you have any questions or need further explanation.