Siemens SIMATIC S7-300 FM 350-1 Manual page 28

Wiring the FM 350-1
3.1 Pin assignments of the front connector
Auxiliary Voltage 1L+/1M
Connect a direct voltage of 24 V to the 1L+ and 1M terminals for the voltage supply of the
5 V and 24 V encoders.
An integral diode protects the module from reverse polarity of the auxiliary voltage.
The module monitors the connection of the auxiliary voltage.
5.2 V DC encoder supply
The module generates a voltage of 5.2 V from the auxiliary voltage 1L+/1M at a maximum
current of 300 mA that is available at the `5.2 VDC' connection for the short-circuit-proof
supply of a 5 V encoder. The encoder supply is monitored for short-circuit.
24 V DC encoder supply
For the 24 V voltage supply of an encoder, the voltage 1L+/1M is made available and short-
circuit proof at the `24 VDC' output. The encoder supply is monitored for short-circuit.
5 V Sensor Signals A and /A, B and /B, N and /N
You can connect incremental encoders with 5 V differential signals to the front connector in
accordance with RS 422, that is, incremental encoders with the differential signals, A and /A,
B and /B, N and /N.
The signals A and /A, B and /B, N and /N are connected via the correspondingly labeled
terminals.
The signals N and /N are only connected if you want to set the counter to the zero mark of
the encoder.
The inputs are not isolated from the bus of the S7-300.
24 V Encoder Signals A*, B* and N*
24 V signals are represented by the letters A*, B* and N*.
You can connect three different encoder types to each counter:
● Incremental encoders with 24 V signals:
● Pulse encoders without direction level:
● Pulse encoders with direction level:
The inputs are not isolated from the bus of the S7-300.
28
The signals A*, B* and N* are connected via the correspondingly labeled terminals.
The signal is connected to terminal A*.
The count signal is connected to terminal A*. The direction level is connected to terminal
B*.
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01