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The PXI star trigger is a feature implemented on National Instruments PXI chassis. PXI chassis have a PXI trigger bus that is linked to all slots in the chassis. In addition, PXI chassis have a star trigger that is linked to Slot 2. The star trigger is a high-performance trigger signal that you can use to synchronize all the modules in a chassis. You can also do this using the normal PXI trigger bus, but the star trigger offers increased performance, specifically a propagation delay of no more than 5 ns and an intermodule delay of no more than 1 ns.
Slot 2 of the PXI chassis is optimized for a star trigger controller. If the star trigger is not required, you can use Slot 2 as a standard peripheral slot. The trigger signal generated by a controller can then be accessed by the other modules through the backplane. The star trigger controller in Slot 2 of the PXI chassis can route triggers among peripheral slots with very low skew (within 1 nanosecond).
To use a star trigger, the digitizer must be in a PXI form factor.
All NI digitizers can receive triggers from the PXI star trigger line, which means that if another instrument is driving the PXI star trigger from Slot 2 of the PXI chassis, the NI digitizer can receive this trigger signal from another slot. NI digitizers cannot drive the PXI star trigger line from Slot 2. Therefore, if you want to generate a trigger on the star trigger line with a master in Slot 2, this master cannot be an NI digitizer.