Serial Communication Converters & Adapters Instruction Manual
9
Figure 5. RS-485 Two-Wire Multi-Drop
Wiring
Notes:
1. Termination resistors are optional and
values depend on the cable length and
characteristic impedance. Consult the
cable manufacturer for
recommendations.
2. Refer to RS-232 to RS-485 Converter
documentation for further details.
3. Use shielded cable, twisted-pair plus
ground. Connect ground shield only at
one location.
Connections
A Cat5e cable is provided to connect the P
RO
V
U
meter to the PDA1485 adapter.
Figure 6 details the wiring connections from the
PDA1485 to an RS-422/485 serial converter
(such as the PDA7485 or PDA8485) for a four-
wire network.
PDA1485 to RS-422/485 Serial Converter
Connections
RS-422/485 Serial
Converter
PDA1485
RS-485 Adapter
DO
DI
DO
DI
DI
DO
DI
DO
Figure 6. Connections for PDA1485 to
Serial Converter
If the serial converter is configured for a two-wire
network then the requirement to externally wire
the DO to the DI and the /DO to the /DI on the
PDA1485 screw terminal connector is needed.
