Siemens SINAMICS G120 Operating Instructions Manual page 153

A difference in the ground potential between the master and slaves in an RS 485 network
can damage the inverter Control Unit. You must make absolutely sure that the master and
slaves have the same ground potential.
SUB D connection on the CU 240S (pin assignment)
The CU240S Control Units are equipped with a 9-pole SUB D socket for connecting the
inverter via an RS 485 interface. A standard 9-pole SUB D connector with a 180° cable outlet
can be used for the USS connection via RS 485.
Table 5- 67
Cable lengths and number of devices
Table 5- 68
Baud rate in bit/s
2.400 ... 93.750
115.200 (max. baud rate)
CU240S and CU240E Control Units, FW 3.2
Operating Instructions, 03/2009, A5E02440075B AA
CAUTION
Contact assignment of the 9-pole SUB D socket
Con Designation
tact
1 -
2 -
3 RS 485P
4 -
5 0 V
6 -
7 -
8 RS 485N
9 -
X Shield
(housing)
Max. no of devices and cable length
Description
Unused
Unused
Receive and transmit signal (+)
Unused
Ground reference
Unused
Unused
Receive and transmit signal (-)
Unused
Equipotential bonding
Max. no. of devices
32
30
5.11 Operation in fieldbus systems
Max. cable length
1200 m
1000 m
Functions
153