Siemens S7-300 - 3 Inner Diagram; 4 ETH Adapter CN Installation

Panel communication indicator: there are three LED indicators on the panel, and its working state
as the following table:
Indicator Light on Flash Extinguish
PWR（Red）
Power supply normal Fault Fault or no power
TxD（Yellow）
Fault or signal
polarity reversal
Serial port is
receiving the date
Fault or no
communication
RxD（Green）
Fault or signal
polarity reversal
Serial port is
sending the date
Fault or no
communication
3. Inner Diagram
Why the 24V power,RJ45 port and RS485 three parties all need to be isolated?That’s because the
7 pin and 2 pin(output 24VDC power) and RS485 interface(DB9F socket 3、4、5、6、8、9pin) on
the PLC PROFIBUS socket are isolated,if the adapter is not isolated,it will damage the PLC
isolation system,then damage the PLC or cause interference.
4.ETH Adapter CN installation
You can put the ETH Adapter CN on your desk or install it on the rail of control cabinet.It has the
mounting bracket accessory.User can self-make an Aluminum board with thickness 1.5mm～
2.5mm,then install the adapter on the S7-300/400PLC rail or 35MM standard rail.
- 8 -