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.
DS3 Termination switch ON
Serial RS485 installation
DS3 Termination switch ON
Serial RS485 installation with connector boxes and stubs
| | | | DS3 Termination |
DS3 Termination | | DS3 Termination | |
| | |
switch ON | | switch ON | | switch ON |
| | |
| | | | |
| | | | |
Correct RS-485 star wiring with RS-485 distributor
Incorrect RS-485 star wiring !
16 | EPTZ100_ma_en_rev03.doc |
