Siemens LOGO! Manual page 44

LOGO! installation and wiring
2.3 Wiring LOGO!
Connecting a two-wire sensor to the LOGO! AM2
Wire up the two-wire sensor's connecting wires as follows:
1. Connect the sensor's output to connection U (0 ... 10 V voltage measurement) or to
connection I (0/4 ... 20 mA current measurement) of the AM2 module.
2. Connect the plus connector on the sensor to the 24 V supply voltage (L+).
3. Connect the ground connection of the current output M (on the right side of the sensor, as
shown in the figure above) to the corresponding M input (M1 or M2) on the AM2 module.
LOGO! AM2 PT100
You can connect a maximum of two 2-wire or 3-wire PT100 sensors or one 2-wire plus one
3-wire PT100 sensor to the module. Note that the sensor type supported by the module is
only PT100 with the default temperature coefficient of α= 0.003850.
For a 2-wire connection, you need to short-circuit terminals M1+ and IC1 or M2+ and IC2.
Errors caused by the ohmic resistance of the measuring line are not compensated for this
type of connection. A line resistance of 1 Ω is proportional to measuring error of +2.5 °C.
A 3-wire technique suppresses the influence of the cable length (ohmic resistance) on the
result of the measurement.
LOGO! AM2 RTD
You can connect a maximum of two PT100 sensors or two PT1000 or one PT100 plus one
PT1000 sensor in a 2-wire or 3-wire connection or in a mixed use of 2-wire and 3-wire
connection to the module. Note that the sensor type supported by the module is only PT100
or PT1000 with the default temperature coefficient of α= 0.003850.
For a 2-wire connection, you need to short-circuit terminals M1+ and IC1 or M2+ and IC2.
Errors caused by the ohmic resistance of the measuring line are not compensated for this
type of connection. If a PT100 sensor is connected, a line resistance of 1 Ω is proportional to
measuring error of +2.5 °C; if a PT1000 sensor is connected, a line resistance of 1 Ω is
proportional to measuring error of +0.25 °C.
A 3-wire technique suppresses the influence of the cable length (ohmic resistance) on the
result of the measurement.
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Manual, 10/2017, A5E01248535-AA
LOGO!