National Instruments NI 781xR - Manual (Page 23)

Chapter 2 Hardware Overview of the NI 781xR
© National Instruments Corporation 2-5 NI 781xR User Manual
lines are labeled RTSI/TRIG<0..6> and RTSI/OSC. On the NI PXI-781xR,
the RTSI trigger lines are labeled PXI/TRIG<0..7>. In addition, the
NI PXI-781xR can use the PXI star trigger line to send or receive triggers
from a device plugged into Slot 2 of the PXI chassis. The PXI star trigger
line on the NI PXI-781xR is PXI/STAR.
The NI 781xR can configure each RTSI trigger line as either an input or an
output signal. Because each trigger line on the RTSI bus is connected in
parallel to all the other RTSI devices on the bus, only one device should
drive a particular RTSI trigger line at a time. For example, if one
NI PXI-781xR is configured to send out a trigger pulse on PXI/TRIG0,
the remaining devices on that PXI bus segment must have PXI/TRIG0
configured as an input.
Caution Do not drive the same RTSI trigger bus line with the NI 781xR and another device
simultaneously. Such signal driving can damage both devices. NI is not liable for any
damage 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
Software Specification Revision 2.1 at
www.pxisa.org for more
information about PXI triggers.
PXI Local Bus
The NI PXI-781xR can communicate with other PXI devices using the PXI
local bus. The PXI local bus is a daisy-chained bus that connects each PXI
peripheral slot with the adjacent peripheral slot on either side. For example,
the right local bus lines from a given PXI peripheral slot connect to the left
local bus lines of the adjacent slot on the right. Each local bus is 13 lines
wide. All of these lines connect to the FPGA on the NI PXI-781xR, and you
can use these lines as you use any of the other NI PXI-781xR DIO lines.
The PXI local bus right lines on the NI PXI-781xR are PXI/LBR<0..12>.
The PXI local bus left lines on the NI PXI-781xR are
PXI/LBLSTAR<0..12>.
The NI PXI-781xR can configure each PXI local bus line as either an input
or an output signal. Only one device can drive the same physical local bus
line at a given time. For example, if an NI PXI-781xR is configured to drive
a signal on PXI/LBR0, the device in the slot immediately to the right must
have its PXI/LBLSTAR 0 line configured as an input.