9-8 | ni.comChapter 9 Digital Routing and Clock GenerationPXI Clock and Trigger SignalsPXI clock and trigger signals are only available on PXI/PXI Express devices.PXI_CLK10PXI_CLK10 is a common low-skew 10 MHz reference clock for synchronization of multiplemodules in a PXI measurement or control system. The PXI backplane is responsible forgenerating PXI_CLK10 independently to each peripheral slot in a PXI chassis.PXI TriggersA PXI chassis provides eight bused trigger lines to each module in a system. Triggers may bepassed from one module to another, allowing precisely timed responses to asynchronousexternal events that are being monitored or controlled. Triggers can be used to synchronize theoperation of several different PXI peripheral modules.On M Series devices, the eight PXI trigger signals are synonymous with RTSI <0..7>.Note that in a PXI chassis with more than eight slots, the PXI trigger lines may be divided intomultiple independent buses. Refer to the documentation for your chassis for details.PXI_STAR TriggerIn a PXI system, the Star Trigger bus implements a dedicated trigger line between the firstperipheral slot (adjacent to the system slot) and the other peripheral slots. The Star Trigger canbe used to synchronize multiple devices or to share a common trigger signal among devices.A Star Trigger controller can be installed in this first peripheral slot to provide trigger signals toother peripheral modules. Systems that do not require this functionality can install any standardperipheral module in this first peripheral slot.An M Series device receives the Star Trigger signal (PXI_STAR) from a Star Trigger controller.PXI_STAR can be used as an external source for many AI, AO, and counter signals.An M Series device is not a Star Trigger controller. An M Series device may be used in the firstperipheral slot of a PXI system, but the system will not be able to use the Star Trigger feature.PXI_STAR FiltersYou can enable a programmable debouncing filter on each PFI, RTSI, or PXI_STAR signal.When the filters are enabled, your device samples the input on each rising edge of a filter clock.M Series devices use an onboard oscillator to generate the filter clock with a 40 MHz frequency.Note NI-DAQmx only supports filters on counter inputs.The following is an example of low to high transitions of the input signal. High to low transitionswork similarly.Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
