Need help synchronizing a buffered continuous acquisition using multiple E series devices and PCI-DIO-32HS.

[enlmenz]

I currently have a daq application that uses 3 pci-6024e, 2 pci-6033e, and 1 pci-dio-32hs board to acquire a large number of channels continuously using

bufferring. I have noticed some timing problems between signals and suspect that this is due to the fact that the acquisitions are not synchronized between devices. I want to incorporate synchronization into this application. I want to synchronize the acquisition start and to synchronize the clock signals between all devices so that the buffered acquisition starts at exactly the same time on each device and that the scans are acquired at exactly the same time. This way the scans on all channels, regardless of
which device they reside on, will have been acquired simultaneously. My application is used to discern signal timing on a rolling mill for crash analysis. Please advise your recommendations. Should I use RTSI bus to synch up ? Should I use PFI ? I have seen the synch examples for e series devices, but these are set up to acquire only one set of scans, not continuous acquisition. How would these

examples look modified to include synchronizing AI start and Synchronizing clock signals, and doing continuous buffered acq ? Would the AI read go into a loop ?

NI Software : LabVIEW version 7.0
NI Hardware : Select one if your issue is related to hardware device Driver Version : OS : Windows 2000 Customer Information :

Lawrence Menzer
North American Stainless
US
lmenzer@northamericanstainless.com

[George M.]

Hi,

National Instruments makes RTSI Bus Cables to connect up to five DAQ devices. This is due to the fact that most desktop computers only have five internal PCI slots. However, the RTSI Bus was originally designed to support up to eight cabled devices. Since there is not an off-the-shelf RTSI Bus Cable to connect more than five devices, a custom RTSI Bus Cable must be fabricated. This custom cable could consist of two four-connection RTSI cables spliced together.

Another consideration to keep in mind when adding more than five PCI cards to a system is the fact that the PCI Bus only has three DMA channels to share between all the devices on the bus. As the number of PCI devices increases, the overall performance of the devices on the bus will decrease.


An excellent alternative to the PCI/RTSI solution is PXI. Instead of using the RTSI Bus to route timing signals between PCI DAQ boards, the timing signals of PXI DAQ boards are routed via the PXI backplane. The eight-slot PXI-1000B chassis would be the best choice in the above situation. You can find more information at the PXI and Compact PCI page.

I hope this helps, and have a GREAT DAY!