Siemens S7-400 installation manual RS 485 Repeater / Diagnostics Repeater

Networking

5.7RS 485 Repeater / Diagnostics Repeater

Purpose of the Repeater

The RS 485 Repeater / Diagnostics Repeater amplifies data signals on bus cables and couples bus segments.

You need an repeater when:

•More than 32 nodes are connected in the network,

•A grounded segment is to be connected to an ungrounded segment

•The maximum cable length of a segment is exceeded.

Description of the RS 485 Repeater

A detailed description and technical data of the RS 485 repeater can be found in the Reference Manual Module Specifications, Chapter 10.

Assembly

You can install the repeater on a 35 mm standard profile rail.

Wiring the Power Supply Unit

To wire the power supply unit of the repeater, proceed as follows:

1.Open the “M” and “PE” screws.

2.Strip the 24 VDC power supply cable.

3.Terminate the cable to “L+” and “M” or “PE”.

Terminal “M5.2”

Terminal “M5.2” should not be wired because it is only needed during maintenance. Terminal “M5.2” is the reference ground you require when measuring the voltage between terminals “A1” and “B1”.

Connecting the PROFIBUS-DP Bus Cable

For detailed information on hwo to connect the PROFIBUS DP bus cable to the RS 485 repeater, refer to the SIMATIC NET Profibus Networks manual:

Automation System S7-400	Hardware and Installation	5-21
A5E00850741-01