Chapter 2
Hardware Overview of the NI 78xxR
R Series Intelligent DAQ User Manual
2-22
ni.com
The PXI local bus right lines on the NI PXI-781
x
R/783
x
R are
PXI/LBR<0..12>. The PXI local bus left lines on the NI PXI-781
x
R/783
x
R
are PXI/LBLSTAR<0..12>.
The NI PXI-781
x
R/783
x
R can configure each PXI local bus line either as
an input or an output signal. Only one device can drive the same physical
local bus line at a time. For example, if the NI PXI-781
x
R/783
x
R is
configured to drive a signal on PXI/LBR 0, the device in the slot
immediately to the right must have its PXI/LBLSTAR 0 line configured as
an input.
Caution
Do
not
drive the same PXI local bus line with the NI PXI-781
x
R/783
x
R and
another device simultaneously. Such signal driving can damage both devices. NI is
not
liable for any damage resulting from such signal driving.
The NI PXI-781
x
R/783
x
R local bus lines are only compatible with 3.3 V
signaling LVTTL and LVCMOS levels.
Caution
Do
not
enable the local bus lines on an adjacent device if the device drives
anything other than 0–3.3V LVTTL signal levels on the NI PXI-781
x
R/783
x
R. Enabling
the lines in this way can damage the NI PXI-781
x
R/783
x
R. NI is
not
liable for any damage
resulting from enabling such lines.
The left local bus lines from the left peripheral slot of a PXI backplane
(Slot 2) are routed to the star trigger lines of up to 13 other peripheral slots
in a two-segment PXI system. This configuration provides a dedicated,
delay-matched trigger signal between the first peripheral slot and the
other peripheral slots for precise trigger timing signals. For example—as
shown in Figure 2-12—an NI PXI-781
x
R/783
x
R in Slot 2 can send an
independent trigger signal to each device plugged into Slots <3..15> using
the PXI/LBLSTAR<0..12>. Each device receives its trigger signal on its
own dedicated star trigger line.
Caution
Do
not
configure the NI 781
x
R/783
x
R and another device to drive the same
physical star trigger line simultaneously. Such signal driving can damage the
NI 781
x
R/783
x
R and the other device. NI is
not
liable for any damage resulting from
such signal driving.
Summary of Contents for NI 781 R Series
Page 1: ...PXI 7842...
