Siemens SIMATIC ET 200SP Manual page 25

24VDC encoder supply
To supply the encoder and sensors at the digital inputs, the technology module supplies the
DC 24V supply voltage at the 24VDC output with reference to M. Voltage is supplied from
the L+/M supply voltage and monitored for short circuits and overload.
24 V encoder signals/count signals
The 24 V encoder signals are designated A, B and N. You can connect the following encoder
types:
● Incremental encoder with signal N:
The signals A, B and N are connected by means of the correspondingly labeled
terminals. Signals A and B are the two incremental signals phase-shifted by 90°. N is the
zero mark signal which returns one pulse per revolution.
● Incremental encoder without signal N:
The signals A and B are connected by means of the correspondingly labeled terminals.
Signals A and B are the two incremental signals phase-shifted by 90°. The N terminal
remains disconnected.
● Pulse encoders without direction signal:
The counting signal is connected to the A terminal. The count direction is specified via the
control interface. The B and N terminals remain disconnected.
● Pulse encoders with direction signal:
The counting signal is connected to the A terminal. The direction signal is connected to
the B terminal. The N terminal remains disconnected.
● Pulse encoders with counting signal up/down:
The up counting signal is connected to the A terminal. The down counting signal is
connected to the B terminal. The N terminal remains disconnected.
The inputs are not electrically isolated from each other. The inputs are isolated against the
backplane bus.
You can connect the following encoders or sensors at inputs A, B and N:
● Sourcing output:
The inputs A, B and N are switched by the encoder or sensor after 24VDC .
● Sinking output:
The inputs A, B and N are switched by the encoder or sensor after ground M .
● Push pull:
The inputs A, B and N are switched by the encoder or sensor alternately after 24VDC and
ground M . Monitoring for wire break is possible with this type of encoder/sensor. The
wire break detection procedure (alternate switching) allows the counter value to change
in the event of an error (wire break) even without count pulses until the wire break is
detected.
Technology Module TM Count 1x24V (6ES7138-6AA00-0BA0)
Manual, 02/2017, A5E33002339-AB
Wiring
3.1 Pin assignment
25