National Instruments NI PXIe-1085, Руководство пользователя

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NI PXIe-1085 Series User Manual
PXIe_SYNC_CTRL
PXIe_SYNC100 is by default a 10 ns pulse synchronous to PXI_CLK10. The frequency of
PXIe_SYNC100 is 10/
n MHz, where n is a positive integer. The default for n is 1, giving
PXIe_SYNC100 a 100 ns period. However, the backplane allows n to be programmed to other
integers. For instance, setting n = 3 gives a PXIe_SYNC100 with a 300 ns period while still
maintaining its phase relationship to PXI_CLK10. The value for n may be set to any positive
integer from 1 to 255.
The system timing slot has a control pin for PXIe_SYNC100 called PXIe_SYNC_CTRL for use
when
n > 1. Refer to Table B-7, XP3 Connector Pinout for the System Timing Slot , for system
timing slot pinout. Refer to Appendix A, Specifications , for the PXIe_SYNC_CTRL input
specifications.
By default, a high-level detected by the backplane on the PXIe_SYNC_CTRL pin causes
a synchronous restart for the PXIe_SYNC100 signal. On the next PXI_CLK10 edge
the PXIe_SYNC100 signal will restart. This will allow several chassis to have their
PXIe_SYNC100 in phase with each other. Refer to Figure 1-8 for timing details with this
method.
Figure 1- 8 . PXIe_SYNC100 at 3.33 MHz Using PXIe_SYNC_CTRL as Restart
PXI_CLK10
PXIe_ S YNC_CTRL
PXIe_ S YNC100
S YNC100 Divider
Re s t a rted Here