3: Installation and Hardware
XPress DR+ User Guide 19
Screw Terminal Serial Connectors Table 3-2. Serial Screw Terminal Pinout for RS422 (4-Wire)
Pin Direction Name Function
1 Output TX+ Transmit Data +
2 Output TX- Transmit Data -
3 Ground GND Signal Ground
4 Input RX+ Received Data +
5 Input RX- Received Data -
Table 3-3. Serial Screw Terminal Pinout for RS485 (2-Wire)
Pin Direction Name Function
1 Bi-directional TX+/RX+ Transmit Data + and Received Data +
2 Bi-directional TX-/RX- Transmit Data – and Received Data -
3 Ground GND Signal Ground
4 Not Applicable Not Applicable Not Used
5 Not Applicable Not Applicable Not Used
Figure 3-4. Screw Terminal Ports
Note: Termination resistors (R = 120 Ohm) are used to match impedance of a
node to the impedance of the transmission (TX) line. Termination resistors
should be placed only at the extreme ends of the data line, and no more than two
terminations should be placed in any single segment of an RS-485 network. The
terminator resistors may not be needed for your application.