National Instruments NI 784xR User Manual

Also see for NI 781xR: User manual User manual

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National Instruments NI 784xR User Manual Manual pdf 42 page image

Chapter 2 Hardware Overview of the NI 78xxR© National Instruments Corporation 2-21 R Series Intelligent DAQ User ManualRTSI Trigger BusThe NI 78xxR can send and receive triggers through the RTSI trigger bus.The RTSI bus provides eight shared trigger lines that connect to all thedevices on the bus. In PXI, the trigger lines are shared between all the PXIslots in a bus segment. In PCI, the RTSI bus is implemented through aribbon cable connected to the RTSI connector on each device that needs toaccess the RTSI bus.You can use the RTSI trigger lines to synchronize the NI 78xxR to any otherdevice that supports RTSI triggers. On the NI PCI-781xR/783xR, the RTSItrigger lines are labeled RTSI/TRIG<0..6> and RTSI/OSC. On theNI PXI-78xxR, the RTSI trigger lines are labeled PXI/TRIG<0..7>.In addition, the NI PXI-78xxR can use the PXI star trigger line to send orreceive triggers from a device plugged into Slot 2 of the PXI chassis.The PXI star trigger line on the NI PXI-78xxR is PXI/STAR.The NI 78xxR can configure each RTSI trigger line either as an input or anoutput signal. Because each trigger line on the RTSI bus is connected inparallel to all the other RTSI devices on the bus, only one deviceshould drive a particular RTSI trigger line at a time. For example, ifone NI PXI-78xxR is configured to send out a trigger pulse on PXI/TRIG0,the remaining devices on that PXI bus segment must have PXI/TRIG0configured as an input.Caution Do not drive the same RTSI trigger bus line with the NI 78xxR and another devicesimultaneously. Such signal driving can damage both devices. NI is not liable for anydamage resulting from such signal driving.For more information on using and configuring triggers, select Help»Search the LabVIEW Help in LabVIEW to view the LabVIEW Help.Refer to the PXI Hardware Specification Revision 2.1 and PXI SoftwareSpecification Revision 2.1 at www.pxisa.org for more information aboutPXI triggers.PXI Local Bus (NI PXI-781xR/783xR Only)The NI PXI-781xR/783xR can communicate with other PXI devices usingthe PXI local bus. The PXI local bus is a daisy-chained bus that connectseach PXI peripheral slot with its adjacent peripheral slot on either side. Forexample, the right local bus lines from a PXI peripheral slot connect to theleft local bus lines of the adjacent slot on the right. Each local bus is 13 lineswide. All of these lines connect to the FPGA on the NI PXI-781xR/783xR.