- 20 -
IM-ENG-116/GB
Warning !
Please remember that – unless the GND signals at both ends are connected to earth – the RS-485 communication
line needs three wires (differential pair plus GND). It is not recommended to use the cable shield as GND connec-
tion (i.e. third wire).
Warning !
Improper supply connections could seriously damage the unit.
RS-485 note:
According to the RS-485 standard you can connected up to 32 devices to a single line of up to 1200 meters (when
your data rate is lower than 100K baud). To get a reliable connection we recommend not to exceed this limits. You
should also verify that the connection cable is compliant with the standard specified requirements (but at low data-
rates you don’t generally have any problem). Finally, don’t forget that for an RS-485 line a suitable termination resi-
stor is required at both ends, and you should switch it On both on the RS232/RS485 converter and on the farthest
Termination Board panel (i.e. on the last device on the RS-485 bus).
