Bosch NurseCall Main Unit - RS-485 Bus Connection

NurseCall Main Unit Installation | en 19
Bosch Security Systems User Manual F.01U.252.699 | V1.1 | 2012.01
3.2.8 Connecting the RS-485
One NurseCall Main Unit and up to 32 NurseCall Relay Units can be connected to an RS-485
bus. Please contact a specialist for a correct installation.
 See Section A.7.4 RS-485 socket (unit rear), page 59 for connector wiring.
Incorrect connection:
Correct connection:
CAUTION!
Do not use a star connection for the RS-485 network!
Relay Unit n
Relay Unit 1
Relay Unit 2
Main Unit
RS-485 bus (1 twisted pair cable)
Relay Unit n
Relay Unit 1
Relay Unit 2
Main Unit
100 Ω
100 Ω
NOTICE!
The NurseCall Main or Relay Units located at the two ends of the bus must be terminated with
a 100 Ohm resistor.