I am trying to figure out how to use the Backplane clock as a reference for my PXI 5411 and PXI 5621 cards. I am using Measurement Studio VC++ to program my complete DAQ, and not sure how to reference the Backplane 10MHz clock when i configure my devices.
In order to Phase-Lock Loop your PXI-5411 High-Speed Source board to the PXI Backplane you need to:
Set the attribute NIFGEN_ATTR_REF_CLOCK_SOURCE to NIFGEN_VAL_PXI_CLK10, so the function generator uses the 10 MHz PXI backplane clock signal as its reference clock.
Set the attribute NIFGEN_ATTR_REF_CLOCK_FREQUENCY to 10,000,000 (10MHz). The PXI Backplane clock is a 10MHz clock signal.
The NI-FGEN driver installs with help and example programs in different programming languages. Go to the Start button>>Programs>>National Instruments>>NI-FGEN to find them. The CVI example (event driven programming language based on C) C:\VXIpnp\WinNT\nifgen\Examples\CVI\Synchronization5404.c shows you the function calls you need in the "runGeneration()" subroutine.
In order to Phase-Lock Loop your PXI-5621 High-Speed Digitizer board to the PXI Backplane you need to:
Configure the board to use the 10MHz clock from the PXI Backplane. To do this, use the function niScope_ConfigureClock and set the attribute NISCOPE_ATTR_INPUT_CLOCK_SOURCE to NISCOPE_VAL_PXI_CLOCK.
Set the output clock source to none. Given that you are not synchronizin two PXI-5620, you do not need to care about the syncPulse on RTSI 0.
The NI-SCOPE driver installs with help and example programs in different programming languages. Go to the Start button>>Programs>>National Instruments>>NI-SCOPE to find them. The CVI example C:\Program Files\National Instruments\MeasurementStudio\CVI\samples\niScope\cvi\5112Sync shows you the function calls you need in the "Generic5112Sync.c" subprogram (see the _configureBoard subroutine). Keep in mind that this program is made for PCI boards, so it assumes that one board is outputting the reference clock for the other one, instead of using the PXI Backplane clock. You will need to make the same calls for PXI form, though, just use the different values for the attributes that I mentioned above.
Hope this helps,
Claudia Lorente Applications Engineer National Instruments http://www.ni.com/ask