Serial Communication Converters & Adapters Instruction Manual
30
Installation
The DIP switch SW1 allows for several different options. Factory set-
tings for the switch are shown in Figure 13.
1 2 3 4 5
Figure 13. PDA7485 Terminal Connectors and DIP Switch
The TERM switch position adds an internal 120 ohm termination resistor
when ON (up). Termination should be used on both ends of the network
with high data rates and long wiring runs.
To configure a two-wire network set both of the 2 WIRE switch positions
to ON (up). For a four-wire network set both of the 2 WIRE switches to
OFF (down).
When the RS422 switch position is ON (up) it is configured for an
RS-422 network. For RS-485 networks set the RS422 switch to OFF
(down).
The ECHO switch position allows the data being sent from the RS-232
port to be echoed back into the RS-232 port. In most networks, this is
an undesired effect and the ECHO switch would be OFF (down).
Figure 14. PDA7485 DIP Switch Settings
PDA7485 DIP Switch Settings
SW1 Switch Position
ON Setting Function
1
Network Termination Included
(120 ohm)
2
2-Wire Network Mode Connection
(factory setting)
3
2-Wire Network Mode Connection
(factory setting)
4 RS-422
Mode
5 ECHO
Mode
