Network Management Card – User Manual 34003991EN/EB Page 80/118
7.2.2.1 RS485 connection
The EIA RS485 link, 2 wires or 4 wires, must be polarized at a unique point of the link and must be adapted at both
ends for a good working.
Normally, the master of the network sets the polarity of the line. The INMC card is a slave equipment and don’t have
polarisation resistor.
The two ends of the line must be terminated. Allow for 1 or 2 terminators to avoid mismatching the line when any
equipment at the end of the line is disconnected.
The next figure gives the detail of the RS485 connector and the internals drivers:
Pin number Function
1 R- : Receiver - (input)
2 R+ : Receiver + (input)
3 T- : Transmitter - (output)
4 T+ : Transmitter + (output)
5 0 V
Important notes:
Use twisted pair cable (cable specification 0.3mm
2
and capacitance 42pF/m)
The transmission range will increase if a cable with lower capacitance and larger diameter is used.
Use shielded cable in heavy industrial environments.