3 half bridges – Campbell Scientific CR9000X Measurement and Control System User Manual
Page 234
Section 7. Measurement Instructions
7-10
voltage to excite the sensors hooked up to an excitation channel. See examples
below.
Example 1: Bridge type: Full Bridge strain, using 350 ohm gauges resulting in
a total bridge resistance of 350 ohms. If using 5000 mV excitation, how many
gauges can be connected to each excitation channel?
ExVolt
SensorR
PortMaxI
Sensor
Ч
=
#
5
.
3
5000
350
50
#
=
Ч
=
mV
ohm
mA
Sensor
We can Excite 3 Sensors with 5000 mV.
Example 2: Bridge type: Same as Example 1. If it is required to use 4 gauges
per excitation channel, what is the maximum excitation voltage that can be
used?
#
Sensor
SensorR
PortMaxI
ExVolt
×
=
mV
ohm
mA
ExVolt
4375
4
350
50
=
×
=
See Section 3.1.5 Bridge Resistance Measurements and 3.1.6 Measurements
Requiring AC Excitation for more information on Bridge Excitation.
7.3.3 Half Bridges
BrHalf (Dest, Reps, Range, ASlot, SEChan, ExSlot, ExChan, MesPEx,
ExmV, RevEx, SettlingTime, Integ, Mult, Offset)
X = result w/mult = 1, offset = 0
X
V
V
R
R
R
X
S
S
f
=
=
+
1
(
)
s
s
f
f
s
R
X
R
R
X
X
R
R
−
=
−
=
1
1
This Instruction applies an excitation voltage, delays a specified time and then
makes a single ended voltage measurement. The result with a multiplier of 1
and an offset of 0 is the ratio of the measured voltage divided by the excitation
voltage.
See Section 3.1.5 Bridge Resistance Measurements for more information.