Campbell Scientific CR9000X Measurement and Control System - Manual (Page 227)

Section 7. Measurement Instructions
7-3
7.1 Voltage Measurements
VoltDiff (Dest, Reps, Range, ASlot, DiffChan,
RevDiff, SettlingTime, Integ, Mult, Offset)
Parameter
& Data Type
Enter VOLTDIFF PARAMETERS
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 of the Reps.
Reps
Constant
The number of repetitions for the measurement.
Range The voltage range for the measurement.
Constant ± 5 Volt Analog Input
Module (Raw output: mVolt) ± 50 Volt Analog Input
Module (Raw Output: Volt,
except mV500 Range: mV) CR9058E* Isolation Module (Raw
Output: mVolt)
Alpha
Code
Num
Code
R *
Option
Code
Voltage
Range
(±mV)
Alpha
Code
Num
Code
R *
Option
Code
Voltage
Range
±
Alpha
Code
Num
Code
R * Option
Code
Voltage Range
mV5000 0 100 5000 V50 6 N/A 50 V V60 24 N/A ± 60 V
mV1000 1 101 1000 V10 7 N/A 10 V V20 25 N/A ± 20 V
mV200 4 104 200 V2 10 N/A 2 V V2 10 N/A ± 2 V
mV50 5 105 50 mV500 11 N/A 500 mV V2C 22 N/A ± 2 V
mV200C 16 116 200 Alpha Codes ending with a C signify that the channel will be pulled into
See Section
3.1.2.2 for
more info on
the C & R
range code
options. mV50C 17 117 50 Operational Input Voltage Limits & checked for open input. See Section 3.1.2.2
Differential Voltage Range for details.
ASlot
Constant
The number of the slot that holds the Analog Input Module to be used for the measurement.
DiffChan
Constant
The differential channel number on which to make the first measurement. When Reps are used,
subsequent measurements will be made on the sequential differential channels. Enter a negative number
to dwell on that channel for the number of measurements specified by the Reps parameter (except for
CR9058E).
RevDiff
Constant
Option to reverse inputs to cancel offsets. The sign corrected average of these measurements is used in
the result. This technique cancels voltage offsets in the measurement circuitry but requires twice as
much time to complete the measurement. (CR9058E: All channels on a module must have same setting.)
Value Description
0 Inputs are not reversed.
1 A second measurement is made after reversing the inputs
SettlingTime
Constant
The time in microseconds to delay between setting up a measurement (switching to the channel, setting
the excitation) and making the measurement (10 microsecond resolution). See Section 3.1.3 Signal
Settling Time. Enter 0 when using the CR9058E (Settling Time not used).
Entry Voltage
Range
Delay CR9055 Voltage
Range
Delay
0 ± 50 mV 20 µS (default) ± 0.5V 40 µS (default)
0 ± 200 mV 20 µS (default) ± 2 V 40 µS (default)
0 ± 1000 mV 10 µS (default) ± 10 V 30 µS (default)
0 ± 5000 mV 10 µS (default) ± 50 V 30 µS (default)
> 0 all Truncate to closest 10 µS all Truncate to closest 10 µS
Integ
Constant
The integration time in microseconds for each of the channels measured (10 microseconds resolution).
CR9058E*:100 microsecond resolution. All channels on a CR9058 module must have same integration.
Mult, Offset
Constant,
Variable,
Array, or
Expression
A multiplier and offset by which to scale the raw results of the measurement. See the measurement
description for the units of the raw result; a multiplier of one and an offset of 0 are necessary to output in
the raw units. CR9050, CR9051E, and CR9058E raw output is in mVolts. CR9055(E) raw output is in
mVolts for the 500 mV range and Volts for all other ranges.