Chapter 4
Theory of Operation
©
National Instruments Corporation
4-19
Figure 4-16.
Block Diagram of SCXI-1314/SCXI-1520 Combination
Lo
wpass
Filter
Lo
wpass
Filter
Inst.
Amp
.
X1 or X20
T
rac
k and
Hold,
X
1
Null
Compensation
Coarse
–X1
–
+
Shunt Calibr
ation Switches
Half-
Br
idge
Completion
Output
Amp
Output
Amp
–
P0+
RS0+
S0–
S0+
P0–
SCA0
SCB0
SCB0
Shunt Cal A
Shunt Cal B
Quar
ter-Br
idge
Completion
QTR
RS0–
SCA0
Scre
w
T
er
minals
to Field
Wir
ing
SCXI-1314
T
er
minal
Bloc
k
+
SCXI-1520 Module
Multiplexer
Control
Analog
Multiplexer
To
Analog
Bus
Scan Clock
Rear Signal Connector
SCXIbus Connector
Buffer
Digital Interf
ace
and Control
CH7+
Analog
Bus
Switch
Calibr
ation
Source
V
ar
iab
le Gain
X
1 to
X
50
CH7–
Excitation
V
oltage
Setting
Null
Compensation
Fine
B
A
CH0+
CH0–
S1+
S7+
Signal Conditioning (see abo
v
e)
Signal Conditioning (see abo
v
e)
RS+
RS–
S0+
RS0+
RS0–
S1+
S7+
Signal Conditioning
CH1+