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Appendix A Specifications
The following assumptions are made regarding the received IRIG-B signal. All conditions must
be met for the NI PXI-6683 Series to be able to synchronize accurately:
• Seconds begin every minute at 0, increment to 59, and then roll over to 0.
• Minutes begin every hour at 0, increment to 59, and then roll over to 0.
• Hours begin every day at 0, increment to 23, and then roll over to 0.
• Days begin every year at 1. Days increment to 365 in non-leap years, or to 366 in leap years,
and then roll-over to 1. Leap years must be supported. Valid values for year are 01 to 99,
inclusive. Years are assumed to be in the XXI Century. For instance, year 09 represents
2009. If the year is not supplied (sent as 00), the OS system time is read and the year is
derived from it.
To achieve proper synchronization of the NI PXI-6683 Series ensure that the IRIG-B source used
conforms to the requirements listed above. Note that most IRIG-B sources conform to these
requirements.
PXI_STAR Trigger Characteristics (NI PXI-6683 only)
Output-to-output skew,
PFI to PXI_STAR routes
1,2
...............................<400 ps
Output-to-output skew, synchronous triggers...<2 ns, typical
Asynchronous delays, t
pd
PXI_STAR<0..12> to
PFI<0..2> output .......................................8.5 ns, typical
PXI_STAR<0..12> to
PXI_TRIG<0..7> output ...........................10 to 18 ns, typical
PXI Trigger Characteristics
Output-to-output skew
1
.....................................<5 ns, typical
Asynchronous delay, t
pd
PXI_TRIG<0..7> to
PFI<0..2> output .......................................13 to 23 ns, typical
1
Measured at the NI PXI-6683 Series backplane connector.
2
Applies to asynchronous routes from a single PFI input to multiple PXI_STAR outputs.
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