User Manual

VDIV10.1, VDIV2.1 Voltage Divider Terminal Input Modules
Datalogger
H
L
AG or
G or
Shields
SENSOR
Signal
Ground
H
L
G
SENSOR
Signal
Ground
FIGURE 3-2. Wiring for Single-Ended Voltage Measurements
TABLE 3-1. VDIV10.1 or VDIV2.1 Connections to
Campbell Scientific Dataloggers
Function Label/Lead
CR10X,
CR510
CR800, CR850,
CR3000, CR5000,
CR23X, CR1000 21X/CR7
Output High H 1H 1H 1H
Output Low L 1L 1L 1L
Ground G AG
4. Programming
The output of the voltage divider is measured with the appropriate voltage
measurement instruction. A differential input is measured with the differential
voltage instruction (P2 with the CR23X, CR10(X), 21X, or CR7; VoltDiff with
the CR800, CR850, CR3000, CR5000, CR9000(X), CR1000). A single-ended
input is measured with the single-ended voltage instruction (P1 with the
CR23X, CR10(X), 21X, or CR7; VoltSE with the CR800, CR850, CR3000,
CR5000, CR9000(X), CR1000). Select the smallest input voltage range that
will accommodate the maximum expected output. The smallest possible range
will provide the best resolution.
4.1 Example
For example, suppose we want to measure the voltage of a 12 volt battery
system that may actually experience voltages in excess of 14 volts. Using the
VDIV10.1 10:1 voltage divider, the 14 volt output will be divided to 14/10 =
1.4 volts or 1400 mV. Thus the voltage range on which to make the
measurement is the ±2500 mV range on the CR10(X), CR800, CR850, and
CR1000, the ±5000 mV range on the CR23X, 21X, CR3000, CR5000, and
CR9000(X), and the ±1500 mV range on the CR7.
The multiplier to use with the voltage measurement must take into account the
divisor, the calibration of the sensor, and the units desired for the result. In
this example, voltage is divided by 10 and read by the datalogger as millivolts
(i.e., (V/10) x 10
3
= V x 10
2
). To output directly in volts, we use a multiplier
of 0.01.
3