Specifications

SECTION 6 COMMUNICATIONS

RS422

9 Pin Connector

FUNCTION DESCRIPTION

1 SG signal ground

2 CTS+ clear to send

3 CTS- clear to send-

4 TD+ transmit data+

5 TD- transmit data-

6 RTS+ request to send+

7 RTS- request to send-

8 RD+ receive data+

9 RD- receive data-

TABLE 13: RS422 Connector Pinout

HANDSHAKING SIGNALS

There are two "handshaking" signals: RTS (Request to Send) and CTS (Clear to Send). Some devices

use these handshaking signals and others do not. It is important to know if your device supports certain

handshake signals. Anaheim Automation Indexers support both of these signals.

DTE VS DCE

(THE COMPUTER IS THE DTE......THE INDEXER IS THE DCE)

Signal 9 PIN

Connector

DIRECTION FUNCTION

SG 5 0 VDC Signal Ground

TD 3 DTE to DCE transmitted data

RD 2 DCE to DTE received data

RTS 7 DTE to DCE request to send (DTE ready)

CTS 8 DCE to DTE clear to send (DCE ready)

TABLE 14: Pin Description for RS232 with a DB9

There are two types of devices defined. The first is called DTE (data terminal equipment). Examples of

this would be a terminal, or an IBM Compatible Computer. The second type of device is a DCE (data

communication equipment). Examples of this would be a modem or an Anaheim Automation Indexer such

as the SMC40. DTE's have input pins of one type corresponding to output pins on the DCE's.

NOTE: THE SIGNAL NAMES ARE FROM THE POINT OF VIEW OF THE DTE COMPUTER. FOR

EXAMPLE, PIN 3 IS CALLED TD (TRANSMIT DATA) BY BOTH SIDES, EVEN THOUGH THE DTE

(COMPUTER) SENDS IT AND THE DCE (SMC40) RECEIVES IT.

With a DB9, a DTE (such as a computer) transmits on pin 3 and receives on pin 2.

With a DB9, a DCE (such as a SMC40) transmits on pin 2 and receives on pin 3.