User manual

Operating Instructions OPUS20E For external sensors
7
EN
7
.2.3 Pt100 Sensors in 3-wire and 4-wire Circuit
In the case of the 3-wire circuit, the Pt100 sensor is connected to the measure-
ment circuit using 3 wires. The measuring current is fed into the sensor via line
D0/D1. The resistance of the Pt100 sensor is determined from the terminal volt-
ages B0/B1, C0/C1 and D0/D1:
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I
mportant: The OPUS20E is capable of compensating line
resistances of up to 10 Ω. Compensation typically reduces the
effect of the line resistance by a factor of 100.
In the case of the 4-wire circuit, the Pt100 sensor is connected to the measure-
ment circuit using 4 wires. The measuring current is fed into the sensor via
lines D0/D1 and C0/C1. The resistance of the Pt100 sensor is determined from
the terminal voltages B0/B1 and A0/A1:
For precise temperature measurement, the 4-wire circuit is preferable.
To log on and configure Pt sensors on the data logger,
follow the instructions in chapter 7.3.
7.2.3 Thermocouples
The data logger supports the connection of type J, K and S thermocouples. The
positive pole of the thermocouple is connected to terminal B and the negative
pole is connected to terminal A:
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Important: Pay attention to polarity when
connecting thermocouples.
To log on and configure thermocouples on the data logger,
follow the instructions in chapter 7.3.
7.3 Configuring Analog Sensors (M81)
In order to use analog sensors with the data logger, the specification of the
analog sensors must be correctly configured on the data logger.
The configuration process is only available when the data logger is not in
the logging mode (M3 or M4).
To configure the specification of a sensor for the first input channel, use the
mode selection key as described in chapter 6.2 to navigate to configuration
mode M81 (AN0); or to configure the specification of a sensor for the second
input channel, use the mode selection key to navigate to configuration mode
M81 (AN1). The option to configure the first analog sensor is shown on the
display.
D0 / D1
B0 / B1
C0 / C1
Pt100
D0 / D1
B0 / B1
A0 / A1
C0 / C1
Pt100
TC+
TC(-)
B0 / B1
A0 / A1
Sensor
7
.2.1 Voltage Measurement Sensors: 0 - 1V
The positive pole of the voltage source is connected to terminal B and the
negative pole is connected to terminal A, as shown in the diagram:
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Important: The voltage input is a true differential input. If the sensor
is connected to the data logger by means of cables of excessive
length, it may be necessary to connect the sensor using shielded cables.
The cable shield must be connected to the GND terminal.
To log on and configure voltage measurement sensors on the data logger,
follow the instructions in chapter 7.3.
7.2.2 Voltage Measurement Sensors:
2-wire 4 - 20 mA and 3-wire 0 - 20 mA
The circuit supports voltage measurements in 2-wire and 3-wire operation.
The prerequisite for 2-wire operation is that the reference potential of the
power supply to the sensor and the power supply to the OPUS20E must be iden-
tical. In 2-wire and 3-wire operation, the power supply to the sensor is fed
via terminal A0/A1.
Connection diagram for voltage measurement
using the 2-wire technique:
The sensor current is converted into a voltage at a burden resistor in the
OPUS20E. The burden resistor has a resistance of <50 Ω. Both the sensor and
the OPUS20E can be powered via an external voltage source.
Connection diagram for voltage measurement
using the 3-wire technique:
This circuit is used for sensors with power consumption greater than 4 mA,
for example heated gas sensors.
To log on and configure voltage measurement sensors on the data logger, follow
the instructions in chapter 7.3.
Ri
+-
S
ensor
B
0/B1
A0 / A1
GND
Sensor: 4 … 20 mA
External voltage source
A0 / A1
+24V
Sensor
GND
Sensor: 0/4 … 20 mA
External voltage source
A0 / A1
+24V
Sensor