Siemens SIMATIC NET PROFIBUS - Manual (Page 171)

Active Components for RS-485 Networks
5-5
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
Block Diagram
Figure 5-1 shows the block diagram of the RS-485 repeater:
S Bus segment 1 and bus segment 2 are electrically isolated.
S
Bus segment 2 and the PG/OP connector are electrically isolated.
S
Signals are amplified:
– between bus segment 1 and bus segment 2
– between the PG/OP connector and bus segment 2
5V
24 V
Segment 2
A2
B2
A2
B2 Segment 1
A1
B1
A1
B1
PG/OP
socket
L+ (24 V)
M
A1
B1
5 V
M5 V
L+ (24 V)
M
PE
M 5.2
Logic
5V
24 V
1M 1M
Figure 5-1 Block Diagram of the RS-485 Repeater