Compaq 850 manual Serial Interface, 1 RS-232 Interface, DB-9 Serial Connector Pinout

Chapter 5 Input/Output Interfaces

5.4SERIAL INTERFACE

All models include two 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 RS-232 INTERFACE

On the legacy-light system, the UART is associated with a DB-9 connector that complies with EIA standard RS-232-C. The DB-9 connector is shown in the following figure and the pinout of the connector is listed in Table 5-7.

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	--	--	--

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 Deskpro EXS and Workstation 300 Personal Computers

Featuring the Intel Pentium 4 Processor

First Edition – December 2000