VTI Instruments EMX-4016B, Руководство пользователя

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APPENDIX B 47
The key advantage of LAN synchronization is that the user can achieve almost equivalent
synchronization performance between chassis without running additional trigger or clock cables.
Just like trigger line synchronization, the entire system can be triggered by an external trigger signal
connected to one instrument, by sending a trigger command, by sending a LAN event trigger, or by
an analog signal at one of the ADC channels crossing trigger threshold level.
When chassis are separated by a long distance or when LAN communication is slow, a certain
restrictions can apply. For example, when one of analog channel’s detects a trigger, it sends a LAN
message to all chassis so that they trigger at the same time. A problem can occur if the another
channel in the a different chassis also detect a trigger condition before it receives a LAN message
trigger from the first chassis that detected a previous trigger condition. In order to avoid this
confusion, the user may need to set restrictions so that only certain channels can detect trigger
events.
In order to configure LAN synchronization, the EMX-2500’s in each chassis must be configured to
use PTP2 as its Time Source, as shown in Figure 4-10. This allows the chassis to synchronize with
an IEEE 1588 Grandmaster clock on the system. Then, after opening a Digitizer/Dsa driver session,
the
ReferenceOscillator. Source and TimestampSource properties must be set to “System” (IEEE
1588). Once these steps have been completed, the EMX-4250/4350/4380’s Sync.CoordinationLine
property must be set to
“LAN,PXI0”. Once this has been performed, the EMX-4250/4350/4380’s
state transitions will be automatically coordinated by LAN events between chassis and PXI0 trigger
line within chassis.
Figure 4-10: PTP Time Source