ABB REB 551-C3*2.5, Installation And Commissioning Manual, Page: 46 / 148

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Installing the serial communication cable for
RS485 SPA/IEC Chapter 5
Installing the terminal
5 Installing the serial communication cable for
RS485 SPA/IEC
5.1 RS485 serial communication module
Figure 8: Pin arrangement on modem terminal. Baud rate: 9600
The distance between earth points should be < 100 m, see figure 9 . Only the outer shielding is
connected to the protective earth at the terminal. The inner and outer shieldings are connected
to the protective earth at the external equipment. Use insulating tape for the inner shield to pre-
vent contact with the protective earth. Make sure that the terminals are properly earthed with as
short connections as possible from the earth screw, for example to an earthed frame.
The terminal and the external equipment should preferably be connected to the same battery.
Where:
A Signal A
B Signal B
1) Do not use
GND Ground
en03000109.vsd
A
B
1)
1)
1)
GND
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