Rs422 Encoder Signals - Siemens SIMATIC S7-1500 Manual

Wiring

3.2 RS422 encoder signals

3.2 RS422 encoder signals
RS422 encoder signals/count signals
The TM PosInput 2 can process encoder signals that use the RS422 signal standard. These
counting encoder signals are designated with the letters A, B and N.
An RS422 encoder signal uses a pair of wires and the counter information is transmitted as
differential voltage. This ensures interference-free transmission of RS422 encoder signals
even with high frequencies over long distances. The RS422 wire pairs must be twisted
together in the cable.
You can connect the following encoder types:
● RS422 incremental encoder with N signal:
The encoder signals A, B and N are connected using the correspondingly marked
terminals. A and B are the two incremental signals phase-shifted by 90°. N is the zero
mark signal that supplies one pulse per revolution.
● RS422 incremental encoder without N signal:
The encoder signals A and B are connected using the correspondingly marked terminals.
A and B are the two incremental signals phase-shifted by 90°. The N terminals remain
unconnected.
● RS422 pulse encoder without direction signal:
The counting signal is connected to the A terminals. The count direction can be specified
via the control interface. The B and N terminals remain unconnected.
● RS422 pulse encoder with direction signal:
The counting signal is connected to the A terminals. The direction signal is connected to
the B terminals. Counting down takes place at a high level of the direction signal. The N
terminals remain unconnected.
● RS422 pulse encoder with up/down count signal
The up counting signal is connected to the A terminals. The down counting signal is
connected to the B terminals. The N terminals remain unconnected.
The inputs are not isolated from each other. The inputs are isolated from the backplane bus.
Note
The RS422 signal standard offers greater interference immunity than the TTL signal
standard. If your incremental encoder or pulse encoder supports the RS422 and the TTL
signal standard, we recommend using the RS422 signal standard.
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Technology module TM PosInput 2 (6ES7551-1AB00-0AB0)
Manual, 06/2018, A5E03982218-AB