DDS EX
Explosion-Proof Transmitter and Controller Instruction Manual
17
Serial Communications Connections
The DSS EX has a 5-position terminal block for connecting RS-485 serial devices.
Figure 5 details the wiring connections from the DSS EX to an RS-485 serial converter (such as the
PDA7485 or PDA8485) for a four-wire network.
DSS EX to RS-485
Serial Converter Connections
RS-485 Serial
Converter
DSS EX RS-485
Connections
DO
DI
DO
DI
DI
DO
DI
DO
Figure 5: DSS EX Connections to a Serial Converter
The DSS EX has three diagnostic LEDs: a Power (P) LED to show when the module is powered properly,
a Transmit Data (TX) LED to show when the module is being transmitted to by the PC side, and a
Receive Data (RX) LED to show when the module is sending data to a receiving device.
The following diagrams detail how to connect the RS-485 serial communications from the DSS EX to a
RS-485/RS-232 serial converter (PDA7485) in four wire and two wire configurations.
Three Wire Connections
In order to wire the 5 pins for use as a 3-wire half-duplex RS-485 connection, it is necessary to create a
jumper connection between DI – DO and DI- – DO- as shown below.
Figure 6. Three-Wire RS485 Connection
F4 COM
DI
DI DO DO
TX
RX
1 2 3 4 5
1 2
