Design Of The Rs 485 Repeater - Siemens SIMATIC RS 485 Manual

3.2

Design of the RS 485 repeater

The following table shows the design and functions of the RS 485 repeater.
Table 3- 3 Design and functions of the RS 485 repeater
Design of the repeater
s
Note
Terminal M 5.2 of the power supply serves as ground reference for signal measurements in
the event of a fault and should not be wired.
RS 485 Repeater
Manual, 02/2011, A5E03382072-01
no. Function
①
Connection for the RS 485 repeater power supply (pin "M5.2" is the
ground reference, if you want to measure the voltage difference
between terminals "A2" and "B2").
②
Shield clamp for the strain relief and grounding of the bus cable of bus
segments 1 or 2
③
Terminals for the bus cable of bus segment 1
④
Switches for terminating resistance for bus segment 1
⑤
LED for bus segment 1
⑥
OFF switch
(= isolate bus segments from each other, for example, for
commissioning)
⑦
LED for bus segment 2
⑧
Switches for terminating resistance for bus segment 2
⑨
LED 24 V supply voltage
⑩
Terminals for the bus cable of bus segment 2
⑪
Slide for mounting and removing the RS 485 repeater on the standard
mounting rail
⑫
Interface for PG/OP on bus segment 1
3.2 Design of the RS 485 repeater
Description
11