Chapter 3
Signal Connections
©
National Instruments Corporation
3-17
PXI TIO devices
u
se PXI trigger line 7 as their RTSI clock line. The
maxim
u
m timebase provided by the PXI TIO device is phase locked to the
10 MHz PXI backplane clock. By
u
sing other PXI mod
u
les that phase lock
their board clocks to the 10 MHz PXI backplane clock, yo
u
can better
synchronize operation in a m
u
lti-mod
u
le PXI system. The phase locking is
enabled by defa
u
lt and can be disabled by way of software. If the mod
u
le
is
u
sed in a compact PCI chassis that does not have the 10 MHz PXI
backplane clock, the phase locking is a
u
tomatically disabled. Additionally,
PXI trigger line 6 corresponds to PXI star trigger on PXI TIO devices.
Fig
u
re 3-9 shows the RTSI signal connection scheme for PXI TIO devices.
Figure 3-9.
RTSI Signal Connection for PXI
+5 V Power Source
The +5 V pin on the I/O connector s
u
pplies power from the comp
u
ter
power s
u
pply thro
u
gh a self-resetting f
u
se. The f
u
se resets a
u
tomatically
within a few seconds after removal of an overc
u
rrent condition. The power
pin is referenced to the D GND pins and can s
u
pply power to external
digital circ
u
itry. The power rating for this +5 V pin on the NI 660
x
is
+4.65 to +5.25 VDC at 1 A.
PXI Star 6
Ctr
n
Source
Ctr
n
Gate
Ctr
n
Aux
Ctr
n
InternalOutput
20 MHz Timebase
Master Timebase
PXI Trigger 7
R
TSI Bus Connector
R
TSI Switch
R
TSI Switch
PXI Trigger
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