Copyright © 2010 Future Technology Devices International Limited

6

Document Reference No.: FT_000148

USB-COM232-PLUS4 Datasheet

Version 1.2

Clearance No.: FTDI# 97

2 Installation

2.1.1 Wiring

Insert the A-plug into an available USB Host or Hub port. Insert the miniB-plug into the miniB-receptacle

on the USB-COM232-PLUS4.

RS232 cables have followed a standard 9-pin configuration on a D-sub connector since the mid 1980s.

The USB-COM232-PLUS4 follows this standard as a Data Terminal Equipment (DTE) device. If the RS232

equipment being connected is a Data Communication Equipment (DCE) device, it’s typical that a straight-

through cable can be used.

DTE Pin Number

Signal Name

DCE Pin Number

1

DCD = Data Carrier Detect

1

2

RXD = Receive Data

2

3

TXD = Transmit Data

3

4

DTR = Data Terminal Ready

4

5

GND = RS232 signal ground

5

6

DSR = Data Set Ready

6

7

RTS = Request To Send

7

8

CTS = Clear To Send

8

9

RI – Ring Indicator

9

Table 2.1 – RS232 DTE to DCE connection with straight-through cable

If the USB-COM232-PLUS4 is connected to another DTE device, a serial “null-modem” cable is required. A

null-modem cable handles connecting output signals to the corresponding input signals on the other end.

Table 2.3 shows a typical null-modem cable. Note that RI and DCD are not always used.

DTE Pin Number

Signal Name

DTE Pin Number

2

RXD = Receive Data

3

3

TXD = Transmit Data

2

4

DTR = Data Terminal Ready

6

5

GND = RS232 signal ground

5

6

DSR = Data Set Ready

4

7

RTS = Request To Send

8

8

CTS = Clear To Send

7

Table 2.2 – RS232 DTE to DTE connection with null-modem cable

Some serial devices may require certain handshake signals be connected. Refer to your device manual

for cabling details.