American Fibertek RRM-1485-2F8 - Manual (Page 5)

5
RS485 TWO WIRE INPUT / OUTPUT DATA CONNECTIONS
Data input/output connections are made via a terminal block on the back of the unit. An example
of the RS485 interconnection between the RRM-1485-2F8 unit and the copper device to which it
is attached is shown below. This illustration is based on industry standard EIA terminology for
the transmission of electronic data signals.
DATA CONFIGURATION
The RRM-1485-2F8 is shipped from the factory in the RS485 4-wire configuration. In order
to configure the unit for RS485 two wire operation, the unit needs to be opened up and
several switch settings and jumper pins need to be modified using the internal
switch/jumper settings shown on the next page.
The RRM-1485-2F8 is shipped from the factory with internal data input and output 120
ohm terminations switched on. In order to remove the internal terminations, the unit
needs to be opened up and several switch settings need to be modified using the internal
switch/jumper settings shown on the next page.
See page 7 for an explanation of termination and offset bias requirements for RS485 data. To
open the RRM-1485-2F8, remove three screws on top cover to remove cover and access the
switch and jumper locations.