Siemens SINAMICS G180 Installation And Operating Instructions Manual page 106

Operation
8.4 Controlling the external connections of the inverter
● Do not place any gearbox between encoder and motor.
● Use twisted pair cables for the same encoder tracks, e.g. A + / A -.
● Lay the cable shield on both sides at the encoder and inverter connector.
Connecting a TTL encoder to ‑X25
All encoder signals have a voltage level compliant with RS 422.
The encoder connection on the inverter side is a high density socket.
● Only use this encoder for field-oriented control with a speed accuracy < 1 %.
● Connect the encoder mechanically rigid to the motor.
● Do not place any gearbox between encoder and motor.
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Figure 8-18 Sincos encoder at -X25
Figure 8-19 TTL encoder at ‑X25
Installation and operating instructions Sinamics G180
Operating Instructions, 05/2013, 4BS0751-001