RS 485 Repeater
9.1 Fields of application and properties; (6ES7972-0AA01-0XA0)
S7-300 Automation System Module data
9-2 Manual, 08/2006, A5E00105505-04
9.1 9.1 Fields of application and properties; (6ES7972-0AA01-0XA0)
Order number
6ES7972-0AA01-0XA0
Definition of the RS 485 Repeater
The RS 485 Repeater amplifies data signals on bus lines and couples bus segments.
Application of the RS 485 Repeater
You need an RS 485 Repeater if:
● more than 32 nodes are connected to the bus
● bus segments are operated ungrounded on the bus, or
● the maximum cable length of a segment is exceeded (see the table below.)
Table 9-1 Maximum cable length of a segment
Transmission rate Max. cable length of a segment (in m)
9.6 to 187.5 kbps 1000
500 kbps 400
1.5 Mbps 200
3 to 12 Mbps 100
Rules
If you install the bus using RS 485 Repeaters:
● Up to nine RS 485 Repeaters may be connected in series.
● The maximum cable length between two nodes with RS 485 Repeater may not exceed
the values listed in the table below.
Table 9-2 Maximum cable length between two RS 485 Repeaters
Transmission rate Maximum cable length between 2 nodes (in m) with RS 485 Repeater (6ES7972-
0AA01-0XA0)
9.6 to 187.5 kbps 10000
500 kbps 4000
1.5 Mbps 2000
3 to 12 Mbps 1000
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