The Rs 485 Repeater: Scope Of Application; Maximum Cable Length Of A Segment; Maximum Cable Length Between Two Stations - Siemens SIMATIC S5 Manual

RS 485 repeaters: installing, connecting and operating
6.1

The RS 485 repeater: scope of application

What is an RS 485
repeater?
Using the RS 485
repeater
Rules
6-2
An RS 485 repeater amplifies data signals on bus lines and is the link
between individual bus segments.
You must use an RS 485 repeater, if:
you want to connect more than 32 stations to the bus,
you want to operate bus segments as non-grounded segments, or
a segment exceeds the maximum permissible cable length (see Table 6-1).
Table 6-1 Maximum cable length of a segment
Baud rate
9.6 to 187.5 kbaud
500 kbaud
1.5 Mbaud
3 to 12 Mbaud
When you set up a bus with RS 485 repeaters, the following rules apply:
You cannot connect more than nine RS 485 repeaters in a cascade.
If you use RS 485 repeaters with the order number 6ES7 ..., the maximum
cable length between two nodes is subject to the limits stated in
Table 6-2.
Table 6-2 Maximum cable length between two stations
Baud rate Max. cable length between 2 stations (in meters)
9.6 to 187.5 kbaud
500 kbaud
1.5 Mbaud
3 to 12 Mbaud
Max. cable length of a segment (in meters)
1000
400
200
100
with RS 485 repeaters (6ES7 972-0AA00-0XA0)
10000
4000
2000
1000
ET 200 Distributed I/O System
EWA 4NEB 780 6000-02a