Schneider Electric FBZ2 Benutzerhandbuch
20
Communication Guide
The standard connection conforms to the Modbus specifications, sepecially 2 wire
multidrop serial bus diagram, presented at the website of Modbus.org in 2002
(Modbus_over_serial_line_V1.pdf, Nov.2002). Simple wiring diagram is like below.
The characteristics is like below in case of a direct connection to the bus.
Items Contents
Type of trunk cable
single, shielded, twisted pair cable.
Min 3rd cable
Maximum length of the bus
1000m (3,2181 ft) (at 19.2kbps)
Maximum number of
32 stations (31 slaves)
stations without repeater
�
20m (66ft, at 1 tapoff)
Maximum length of tapoffs
�
40m (131ft, divided by tapoff no.
in Multi-Junction Box)
�
450 - 650
Ω
Pullup resistor, 5V basis
�
450 - 650
Ω
Pulldown resistor,
Bus polarization
Recommend the polarization to Master at
Common. There is no polarization at
RS485 of EOCR .
Line terminator
120
Ω
Resistor, + /- 5%
Common polarity
YES (connect 1 protection ground minimum
to the bus)
Standard connection