Siemens SIMATIC NET PROFIBUS manual What is an RS-485 Repeater?, Design of the RS-485 Repeater

Active Components for RS-485 Networks

5.1RS-485 Repeater

What is an RS-485 Repeater?

An RS-485 repeater amplifies data signals on bus cables and links bus segments.

Using the RS-485 Repeater (6ES7 972-0AA01-0XA0)

You require an RS-485 repeater in the following situations:

SWhen there are more than 32 stations (including repeaters) connected to the bus

SWhen electrically isolated bus segments are required or

SWhen the maximum cable length of a segment is exceeded (see Chapter 3 “Network Configuration”).

Rules

If you want to install a PROFIBUS network with RS-485 repeaters, you can connect a maximum of nine RS-485 repeaters in series.

Design of the RS-485 Repeater

Table 5-1 shows the elements of the RS-485 repeater.

5-2	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000