Bb-electronics QSPXP-100 - Manual User Manual download pdf (Page 16)

Making external connections B&B Electronics ExpressCard Serial Adapter User’s Manual

Page 12 Rev 1.00 (July 2007)

Making external connections

The Serial Adapters are equipped with male DB-9 connectors for RS-

232 and with female DB-9 connectors for RS-422/485. The following

figures and tables show the serial port pinouts for RS-232 and RS-

422/485 applications.

RS-232 serial connections

RS-232 devices are classified by their function as either Data

Terminal Equipment (DTE) or Data Communication Equipment

(DCE).

Figure 14 - Use of DTEs and DCEs in a communication link

DTE- and DCE-type devices have complementary pinouts that allow

terminals and modems to connect directly using a one-to-one cable as

shown in Figure 15. Two DTE-type devices can be connected by a

null modem cable. A typical null modem cable is also shown in the

figure.

Figure 15 - Cabling requirements for RS-232 devices

Note: A DTE device is the

communication source. A DCE

device provides a communication

channel between two DTE-type

devices.

Figure 15 illustrates the RS-

232 pinouts for typical DTE-

to-DCE and DTE-to-DTE

cables with 9-pin connectors.

Note: In many applications,

DCEs are unnecessary. This

allows you to use a null modem

cable (modem eliminator cable)

to directly connect two DTE-

type devices.

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Bb-electronics QSPXP-100 - Manual User Manual Page 16