janitza UMG 103-CBM, User Manual And Technical Data

Page: 36 / 62

UMG 103-CBM www.janitza.com
36
8.4 Bus structure
In a bus structure:
·Connect all devices in line according to the mas-
ter-slave principle.
·Each device has its own address.
·One segment contains up to 32 nodes/devices.
At the beginning and end of a segment, the cable
must be terminated with resistors (bus termina-
tion, 120 ohms, 1/4 W)!
·With more than 32 participants, use repeaters
(line amplifiers) to connect segments!
·Devices with bus termination switched on must
be powered.
·It is recommended that the master be placed at
the end of a segment. If the master is replaced
with the bus termination switched on, the bus is
out of operation.
·The bus can become unstable if a slave with bus
termination switched on is replaced or is de-en-
ergized.
·Devices that are not involved in the bus termina-
tion can be replaced without the bus becoming
unstable.
8.5 Termination resistors
At the beginning and end of a segment, the cable
is to be terminated with resistors (120 Ω, 1/4 W).
Right
Wrong
Terminal strip in the switchboard cabinet.
Device with RS-485 interface.
(Without termination resistor)
Device with RS-485 interface.
(With termination resistor on the device)
INFORMATION
The device does not contain an integrated termina-
tion resistor!