Connecting the encoder
ATM60-Cxx 03/2007 49
The PRESET function was not conceived for dynamic configuration operations but as an
electronic adjustment function for commissioning, in order to assign a specific value to the
mechanical angular position of the ATM60-Cxx.
When the PRESET value is set via CANopen, the value must lie within the currently set total
working range (steps per revolution x number of revolutions).
It should be noted that the number of write cycles of the Eeprom is restricted to 1 million cycles.
This means that the memory location can become defective if 1 million write cycles are
exceeded.
12.5 Screening
In an interference-free environment, unscreened cable is permitted. The following reasons support the use of
screened cable in every case:
· An interference-free space exists at best in the interior of screening switch cabinets. However, as soon as
relays are also located in the cabinet, freedom from interference is no longer ensured.
· The use of unscreened cable demands additional protective measures on the bus signal inputs against
overvoltages.
For this reason, it is fundamentally recommended to use screened leads for the bus cable. This
recommendation also extends to any supply cables which may be needed for external voltage supplies.
Double-screened leads are particularly suitable for environments subjected to high EMC. In order to ensure
optimal protection, in this case the outer braided screen and the inner foil screen at both cable ends should
be connected to protective earth over a large area, using an earthing clamp.
12.5.1 Screening rules
When a screened bus cable is used, we recommend that the screen be connected to the protective earth at
both ends with low inductance. This achieves the most optimal EMC. One exception relates to isolated
potentials (e.g. in refineries); here, as a rule only earthing on one side is permitted.
In the sense of optimal EMC, the connection between the cable screen and the protective earth is carried out
via a metallic device casing and the screw connection of the circular plug connector or PG screw fittings.
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