Ixr ix – Campbell Scientific CR5000 Measurement and Control Module User Manual
Page 138
Section 7. Measurement Instructions
7-12
Resistance
used to measure full bridge
H
L
IXR
IX
X = result w/mult = 1,
offset = 0
X
V
I
R
R
R
R
R
R
R
R R
R
R R
R
R
R
R
R
x
bridge
=
=
+
−
+
⎛
⎝
⎜
⎞
⎠
⎟
=
+
−
+
+
+
+
1
3
3
4
2
1
2
3
1
2
2
3
4
1
2
3
4
(
)
(
)
(
)
R
R R
X R
R
R
X R
R
R R
X R
R
R
X R
R
R R
X R
R
R
X R
R
R R
X R
R
R
X R
1
2
4
2
3
4
3
2
1 3
1
3
4
4
3
2
4
1
2
4
1
4
1 3
1
2
3
2
=
−
−
+
+
−
=
−
+
+
+
=
−
−
+
+
−
=
−
+
+
+
(
)
(
)
(
)
Resistance Parameters
Parameter
& Data Type
Enter
Dest
Variable or
Array
The Variable in which to store the results of the instruction. When Reps are used the
results are stored in an array with the variable name. An array must be dimensioned to
have elements for all the Reps.
Reps
Constant
The number of repetitions for the measurement or instruction.
Range
Constant
Alpha Code
Numeric
Code
Voltage
Range
mV5000 0
± 5000 mV
mV1000 1
± 1000 mV
mV200 2
± 200 mV
mV50 3
± 50 mV
mV20 4
± 20 mV
AutoRange 5
mV20 - mV5000 Selects range (Sect. 3.1)
DiffChan
Constant
The differential channel number on which to make the first measurement. When Reps are
used, subsequent measurements will be automatically made on the following differential
channels. If the channel is entered as a negative number, all reps occur on that channel.
IxChan
Enter the current excitation channel number to use to excite the first measurement.
Constant
Alpha
Code
Code/
Channel
Result
IX1 1
Current Excitation Channels
IX2 2
IX3 3
IX4 4
MeasPEx
Constant
The number of sensors to excite with the same excitation channel before automatically
advancing to the next excitation channel. To excite all the sensors with the same
excitation channel, the number should equal the number of Reps. With current excitation,
the sensors must be wired in series when more than one measurement per excitation is
made.
ExuA
Constant
The excitation current in microamps. The allowable range is ±2500 µA. RevEx may be
used to excite with both a positive and negative polarity to cancel offset voltages.
RevEx
Code Value
Result
(Reversing requires twice as much time to complete)
Constant
False
0
Excite only with the current polarity entered
True
≠0
A second measurement is made with the voltage polarity
reversed to cancel offsets
RevDiff
Code Value
Result
(Reversing requires twice as much time to complete)
Constant
False 0 Signal is measured with the high side referenced to the low
True
≠0
A second measurement is made after reversing the inputs to
cancel offsets