AM16/32 Relay Analog Multiplexer
24
6.3 Half Bridge Measurements
Measurements of this type may be subdivided into three categories
based on completion resistance and the presence or absence of
measured excitation. If the sensor's completion resistor(s) are installed
at the datalogger panel (example: a CSI 107 probe modified for
multiplexer use), then three probes per SET may be excited and
measured in “4X16” mode (Figure 12). However, if the circuit is
completed within the sensor (e.g. potentiometers), then excitation,
wiper signal, and ground must be multiplexed. Because excitation and
ground may be multiplexed in common, up to two sensors per SET
may be measured (Figure 13). If measured excitation is required (i.e.
four wire half-bridge), then only one sensor per SET of four may be
measured (Figure 14).
6.3.1 Half Bridge Measurement with Completion Resistor at
Datalogger
Sensor to Multiplexer wiring - up to three half bridges may be
connected to one input SET in “4X16” mode, provided that the
sensors’ three completion resistors are located at the datalogger
(Figure 12).
Multiplexer to Datalogger wiring - Signal lines from the multiplexer
COM terminals tie to three consecutive single-ended analog input
channels. Three precision completion resistors connect from analog
input channels to analog ground in CR10(X) or to “
” in the
CR23X, 21X or CR7.
21x
CR7
CR10(X)
CR23X/
CR5000
"4 X 16" Mode
E
E
H
H
AG
G
E/VX
H
L
L
L
H
H
H
COM H (ODD)
COM L
COM H (EVEN)
COM L
ODD H
ODD L
EVEN H
EVEN L
SHIELD
SENSOR SHIELDS
COM
MUXSIGNAL
SHIELD
FIGURE 12. Half Bridge (Modified 107 Temperature Probe) Hook-up and Measurement.
CR23X/
21X
CR1000/
CR7
CR10(X) CR5000
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