Hengstler Signo 721.2 User Manual page 107

3 Setup and Operation
The plug has to be disconnected from the counter before the cables are fastened
by means of screws or screw-type terminals.
Caution!
It is not allowed to contact the encoder to a direct current line voltage without
protective circuit for EMC. For cable lenths > 30 m a protective circuit is always
necessary!
When programming the input level to TTL an additional protective circuit is
necessary.
We recommend the installation in a metallic environment.
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