PXI-565x Bitstream Stuck at all Zeros/Ones.Hardware: Modular Instruments>>RF Measurement Devices>>PXI-5650, PXI/CompactPCI>>Chassis>>PXI-1000B
Problem: Why is my bistream stuck at all zeros or ones with the NI PXI-565x? Solution: As part of the PXI specification, all PXI chassis have a 10 MHz system reference clock that is routed to all modules in the chassis and is used as a synchronization tool. This reference clock can be overridden by specific modules when they are placed in Slot 2 of the PXI chassis. Under most circumstances, the PXI chassis will resume producing the 10 MHz clock once it is no longer being overridden. However, in older chassis such as the NI PXI-1000B, the chassis does not always resume generation of the system reference clock. The NI PXI-565x uses this PXI 10 MHz reference clock as a source for pseud-random bit sequence (PRBS) generation. If a device located in Slot 2 stops driving the backplane, then there will be no reference clock on the backplane and the NI PXI-565x PRBS output will be invalid. The modulated signals generated by the NI PXI-565x will produce a bitstream that is all zeros or ones. This problem can be confirmed by running the “Reference Clock” example found at: The solution to this problem is to 1) upgrade to newer chassis 2) not drive the system reference clock 3) make sure the PXI reference clock is overridden for the entire generation period. Related Links: Attachments:
Report Date: 04/14/2006 Last Updated: 01/29/2008 Document ID: 3WDASD2W |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
