User manual
Table Of Contents
- Chapter 1 Overview
- Chapter 2 Hardware Functionality
- 2.1 Introduction
- 2.2 RS-232/422/485 Interface (COM1~COM2)
- 2.3 Optional RS-232 Interfaces (COM3~COM4)
- 2.4 LAN: Ethernet Connector
- 2.5 Power Inputs
- 2.6 USB Connector
- 2.7 DVI-I Display Connector
- 2.8 Reset Button
- 2.9 Power Button
- 2.10 Audio
- Chapter 3 Initial Setup
- Appendix A System Settings and Pin Assignments
- A.1 System I/O Address and Interrupt Assignments
- A.2 Board Connectors and Jumpers
- A.3 RS-232 Standard Serial Port (COM3~COM4)
- A.4 RS-232/422/485 Serial Port (COM1~COM2)
- A.5 Ethernet RJ-45 Connector (LAN1~LAN2)
- A.7 PS/2 Keyboard and Mouse Connector
- A.8 USB Connector (USB1~USB4 & CN7)
- A.9 VGA Display Connector
- Appendix B Programming the Watchdog Timer
11 Chapter 2
2.2.5 Terminal Resistor Setup for RS-422/485
The onboard termination resistor (120 Ohm) for COM1/COM2 can be
used for long distance transmission or device matching (Default Open).
Each terminal resistor responds to different channels for RS-422/485.
Usually, these resistors are needed for both ends of the communication
wires and the value of the resistors should match the characteristic imped-
ance of the wires used.
Table 2.1: Terminal Resistor Settings
COM Port Switch No. Pin Setting Description
COM1 SW4 1 ON 120 Ohm between Data+/
Data- (RS-485)
Or 120 Ohm between Tx+/Tx-
(RS-422)
OFF Open (Default)
2 ON 120 Ohm between Rx+/Rx-
(RS-422)
OFF Open (Default)
COM2 SW5 1 ON 120 Ohm between Data+/
Data- (RS-485)
Or 120 Ohm between Tx+/Tx-
(RS-422)
OFF Open (Default)
2 ON 120 Ohm between Rx+/Rx-
(RS-422)
OFF Open (Default)