Hardware Manual COMBILOG 1020
46
Resistance Measurement
Resistance measurement is carried out by means of voltage
measurement at a resistor, measuring the resulting voltage drop.
The constant current required for the resistance measurings is
provided by the internal supply of the datalogger.
For this purpose the sensor module connects a supply point in-
ternally with the analog measurement input via a reference resis-
tor R
o
. The voltage drop U
o
via resistor R
o
is required as a refer-
ence for further signal processing by the module. The resistance
value of the sensor can be calculated from the input signals U
i
as
a multiple of the reference resistor R
o
. Measuring range is be-
tween 0 and 20 k
Ω
.
Note:
The datalogger
COMBILOG 1020
supports resistance
measurement in 2-, 3- and 4-wire technique. With resistance
measurement in 2-wire technique the supply lines cause an addi-
tional voltage drop, thus distorting the measuring result and influ-
encing the measuring accuracy. Therefore it is necessary to pay
attention especially with resistance measurement in 2-wire-
technique. Wires with impedance as low as possible should be
used. Make sure that the leads are well connected to the data-
logger and the sensor. With resistance measurement using 3-
wire technique the potential on the supply lines will be subtracted
by software. Therefore 2 measurements are necessary, resulting
in double measuring time. With resistance measurement in 4-wire
technique the drop of potential is picked up directly at the sensor,
so that the measuring results are not influenced by the supply
lines.
Summary of Contents for COMBILOG 1020
Page 1: ...COMBILOG 1020 Datalogger Hardware Manual Version 3 09...
Page 2: ...Hardware Manual COMBILOG 1020 2 Issue 03 11 2005 Technical data are subject to change...
Page 4: ...Hardware Manual COMBILOG 1020 4...
Page 6: ...Hardware Manual COMBILOG 1020 6...
Page 12: ...Hardware Manual COMBILOG 1020 12...
Page 86: ...Hardware Manual COMBILOG 1020 86 Bild 8 1 Example Master Slave System...
Page 169: ...Hardware Manual COMBILOG 1020 169...
Page 170: ...Hardware Manual COMBILOG 1020 170...