7.2.2 RS485 link configuration and connection
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
2
R+ : Receiver + (input)
3
4
T+ : Transmitter + (output)
5
0 V
Important notes:
Use twisted pair cable (cable specification 0.3mm2 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.
Network Management Card – User Manual | 34003991EN/EB | Page 80/118 |