EPTZ100_ma_en_rev03.doc 16
3.2.3 RS-485
EPTZ 100 uses RS-485 simplex wiring; the signal is transferred via a single twisted pair line. CAT5
network cable is recommended, UTP version (unshielded) is sufficient for normal application. A shielded
cable should be used if the installed cables are expected to be highly susceptible to interferences.
Basically, the bus should be created by serial wiring, star wiring is only permitted using signal distributors.
Maximum RS-485 bus cable length is 1200 m. Both the first and the last device are normally 120 Ohm
terminated in order to minimize line reflexions.
Serial RS485 installation
Serial RS485 installation with connector boxes and stubs
Correct RS-485 star wiring with RS-485 distributor
Incorrect RS-485 star wiring !
DS3 Termination switch ON
DS3 Termination switch ON
DS3 Termination
switch ON
DS3 Termination
switch ON
DS3 Termination
switch ON