beautypg.com

Siemens SIMATIC NET PROFIBUS User Manual

Page 171

background image

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