User`s guide

9XTend™ RS-232/422/485 RF Modem User’s Guide

2. Interfacing Protocol

The 9XTend RS-232/422/485 RF Modem supports the following interfacing protocols:

• RS-232

• RS-485 (2-wire) Half-duplex

• RS-485 (4-wire) and RS-422

2.1. RS-232 Operation

2.1.1. DIP Switch Settings and Pin Signals

* The ‘Pin Reference Name’ provides an associative tag that references commands used to define pin behaviors.

GPI stands for "General Purpose Input" and GPO stands for "General Purpose Output". As an example, the CD

command is used to define the behavior of GPO2 (DB-9 pin number 1). The ‘Pin Reference Name’ is the name

used when referring to XTend commands and parameters.

Table 2-01. RS-232 Signals and their implementations on the XTend RF Modem

(Low-asserted signals are distinguished by horizontal line over pin name.)

DB-9 Pin

RS-232

Name

Pin Reference

Name*

Description Implementation

1 DCD GPO2 Data-Carrier-Detect Connected to DSR (pin6)

2 RXD DO Received Data Serial data exiting the RF modem (to host)

3 TXD DI Transmitted Data Serial data entering into the RF modem (from host)

4 DTR GPI2 Data-Terminal-Ready Can enable Power-Down on the RF modemy

5 GND - Ground Signal Ground

6 DSR GPO2 Data-Set-Ready Connected to DCD (pin1)

RTS

CMD

GPI1

Request-to-Send /

Command Mode

Provides RTS

flow control or enables Command Mode

8 CTS GPO1 Clear-to-Send Provides CTS flow control

9 RI - Ring Indicator

Optional power input that is connected internally to the

positive lead of the front power connector

Figure 2-01.

RS-232 DIP Switch Settings

DIP Switch settings are read and applied

only while powering-on.

Figure 2-02.

Pins used on the female RS-232 (DB-9)