Serial Interfaces (J15A/B, J11A/B); Figure 3-1. Rs485 Serial Port Implementation - Ampro ReadyBoar 800 Reference Manual

Chapter 3

Serial Interfaces (J15A/B, J11A/B)

The ReadyBoard supports 4 independent serial ports, using two separate chips. The Super I/O controller
(W83627HF) provides Serial ports 1 and 2 through the Serial A DB9 connectors (J15A/B) and the
Southbridge (82801DBM) provides serial ports 3 and 4 through Serial B connector (J11A/B). The four
serial ports support the following features:
•
Four individual 16550-compatible UARTs
•
Programmable word length, stop bits and parity
•
16-bit programmable baud rate generator
•
Interrupt generator
•
Loop-back mode
•
Four individual 16-bit FIFOs
• Serial A supports ports 1 and 2 using the Super I/O Controller
♦
Serial Port 1 (COM1) supports RS232 and full modem support
♦
Serial Port 2 (COM2) supports RS232, and full modem support
• Serial B supports ports 3 and 4 using the Southbridge
♦
Serial Port 3 (COM3) supports RS232/RS485/RS422 and full modem support
♦
Serial Port 4 (COM4) supports RS232/RS485/RS422 and modem support
NOTE
The RS232/RS485/RS422 modes are selected in BIOS Setup under BIOS
and Hardware Settings screen for Serial ports 3 (COM3) and 4 (COM4).
However, the RS232 mode is the default (Standard) for any serial port.
RS485 mode termination is selected with jumper JP5, pins 1-2 (COM3),
and pins 3-4 (COM4), when the RS485 mode is selected in BIOS Setup.
To implement the RS485 mode on either serial port, you must tie the equivalent pins together for each
port.
For example; on Serial Port 3, tie pin 3 (RX3-) to 5 (TX3-) and pin 4 (TX3+) to 6 (RX3+) at the Serial B
interface connector (J3) as shown in Figure 3-1. As an alternate, tie pin 2 to 3 and pin 7 to 8 at the DB9
serial connector for Serial Port 3 as shown in Figure 3-1. Refer also to the following tables for the
specific pins for the other ports and connectors. The RS422 mode uses a four-wire interface and does
not need any pins tied together, but you must select RS485 in BIOS Setup.
Serial B Interface (J11)
for Serial Port 3
(or COM3 Port)
Top View
Tables 3-8 and 3-9 list the pins and corresponding signals for the Serial A interface connector (J15A/B,
Serial Ports 1 and 2) and Table 3-10 list the pins and corresponding signals for the Serial B interface
connector (J11A/B, Serial Ports 3 and 4).
36
19 9 7 5 3 1
10 8 6
20 4 2

Figure 3-1. RS485 Serial Port Implementation

Reference Manual
Standard DB9 Serial
Or
Port Connector (Female)
Rear View
Hardware
1 2 3 4 5
6 7 8 9
ReadyBoard 800