Chapter 5 Input/Output Interfaces

5.4SERIAL INTERFACE

All models include two RS-232-C type serial interfaces to transmit and receive asynchronous serial data with external devices. The serial interface function is provided by the LPC47B357 I/O controller component that includes two NS16C550-compatible UARTs.

Each UART supports the standard baud rates up through 115200, and also special high speed rates of 239400 and 460800 baud. The baud rate of the UART is typically set to match the capability of the connected device. While most baud rates may be set at runtime, baud rates 230400 and 460800 must be set during the configuration phase.

5.4.1 SERIAL CONNECTOR

The serial port uses a DB-9 connector as shown in the following figure with the pinout listed in Table 5-5.

Figure 5-3.Serial Interface Connector (Male DB-9 as viewed from rear of chassis)

Table 5–7.DB-9 Serial Connector Pinout

Table 5-7.

DB-9 Serial Connector Pinout

Pin

Signal

Description

Pin

Signal

Description

1

CD

Carrier Detect

6

DSR

Data Set Ready

2

RX Data

Receive Data

7

RTS

Request To Send

3

TX Data

Transmit Data

8

CTS

Clear To Send

4

DTR

Data Terminal Ready

9

RI

Ring Indicator

5

GND

Ground

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--

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The standard RS-232-C limitation of 50 feet (or less) of cable between the DTE (computer) and DCE (modem) should be followed to minimize transmission errors. Higher baud rates may require shorter cables.

5-8Compaq Evo and Workstation Personal Computers

Featuring the Intel Pentium 4 Processor

Second Edition – January 2003

Page 95
Image 95
Compaq W4000 manual Serial Interface, DB-9 Serial Connector Pinout