Selecting An Incremental Encoder - Siemens SIMATIC FM 351 Installation Manual

10.2 Selecting an Incremental Encoder

Incremental
Only incremental encoders with two pulses having zero marks and offset by
Encoders 90 are supported:
Response Times
The following response time applies to incremental encoders:
Note
You can compensate the response time with appropriate parameterization of
the switchover and switch-off differences.
Example:
An example of the response time:
Response Times
Hardware switching time: approx. 150 µs
Response time = 150 µs
Blurring
Blurring affects the positioning accuracy. With incremental encoders the
blurring is negligible.
Manufacturer We recommend that you use incremental encoders from SIEMENS
(see Appendix B).
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
Encoders with symmetrical output signals with 5 V differential interfaces
conforming to RS422
– Cut-off frequency = 500 kHz
– At 5 V supply voltage: max. 32 m line length.
– At 24 V supply voltage: max. 100 m line length.
Encoders with asymmetrical output signals with 24 V level
– Cut-off frequency = 50 kHz: max. 100 m line length.
Response time = Hardware switching time
Encoders
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