Uss Bus Configuration Via Com Link (Rs485) - Siemens MICROMASTER 440 Operating Instructions Manual

Issue 10/03
3.7.1

USS bus configuration via COM link (RS485)

Using MICROMASTER with RS485 communication requires a proper termination
at both ends of the bus (between P+ and N-), and correct pull up/ pull down
resistors at at least one end of the bus (e.g. from P+ to P10, and N- to 0 V). (refer
to Fig. 3-34)
Control terminals
Fig. 3-34
When the MICROMASTER drive inverter is the last slave on the bus (refer to Fig.
3-35), and there are no other pull up/pull down resistors on the bus, the supplied
terminator must be connected shown in Fig. 3-34).
First Slave
Fig. 3-35
When the MICROMASTER is the first slave on the bus (refer to Fig. 3-35) the
RS485 Terminator may be used to terminate the bus by using P+ and N- only, for
the bus is powered by the last drive as explained.
NOTE
The supply for the pull up/ pull down resistors must be available whenever RS485
communication is in progress!
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0
RS485 Terminator
RS485 Terminator
USS bus configuration
RS485 Terminator
Last Slave
Master
e.g. PLC
RS485 Bus
3 Functions
RS485 Interface
RS485
Terminator
111