© National Instruments
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2-19
Once all of the devices are using or referencing a common timebase, you can synchronize
operations across them by sending a common start trigger out across the PXI_Trig bus and
setting their sample clock rates to the same value as shown in Figure 2-11.
Figure 2-11.
Synchronization Operation
Triggering
The following sections provide details about analog and digital triggering of the NI PXIe-4300
module.
Analog Triggering
You can configure the NI PXIe-4300 analog trigger circuitry to monitor any input channel from
which you acquire data. Choosing an input channel as the trigger channel does not influence the
input channel acquisition capabilities.
The analog trigger signal can be used as a reference trigger only. This restriction is due to the
fact that the analog trigger circuit operates on digitized ADC data, requiring the acquisition to
be running in order for the analog trigger circuit to operate. In a reference triggered acquisition,
you configure the device to acquire a certain number of pre-trigger samples and a certain number
of post-trigger samples.
Extern
a
l
Reference
Clock
÷
200
On
b
o
a
rd
100 MHz
O
s
cill
a
tor
PLL
÷
5
÷
10
PXI_Trig <0..7>
PXIe_CLK100
PXI_
S
TAR
PFI<0,1>
PXIe_D
S
TAR<A,B>
10 MHz RefClk
(To PXI_Trig <0..7>
O
u
tp
u
t
S
elector
s
)
100 MHz
Time
bas
e
20 MHz
Time
bas
e
100 kHz
Time
bas
e
Extern
a
l
Reference
Clock
÷
200
On
b
o
a
rd
100 MHz
O
s
cill
a
tor
PLL
÷
5
÷
10
PXI_Trig <0..7>
PXIe_CLK100
PXI_
S
TAR
PFI<0,1>
PXIe_D
S
TAR<A,B>
10 MHz RefClk
(To PXI_Trig <0..7>
O
u
tp
u
t
S
elector
s
)
100 MHz
Time
bas
e
20 MHz
Time
bas
e
100 kHz
Time
bas
e
M
as
ter
S
l
a
ve
