Serial Communication Converters & Adapters Instruction Manual
12
Figure 10. 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 PDA7420 cable is provided to connect the
Trident meter to the PDA7422 adapter. Figure
11 shows the PDA7420 cable details.
Figure 11. Standard Modular Cable
Wiring
Figure 12 details the wiring connections from the
PDA7422 to an RS-422/485 serial converter
(such as the PDA7485 or PDA8485) for a four-
wire network.
PDA7422 to RS-422/485 Serial Converter
Connections
RS-422/485 Serial
Converter
PDA7422
RS-485 Adapter
DO
DI
DO
DI
DI
DO
DI
DO
Figure 12. Connections for PDA7422 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
PDA7422 screw terminal connector is needed.
(WH) 1
(BK) 2
(R) 3
(G) 4
(Y) 5
(BL) 6
1
2
3
4
5
6
