Module - Allen-Bradley SLC 500 BASIC Installation Instructions Manual

14 SLC 500 BASIC and BASIC-T Modules
Hardware Handshaking
The module uses the following rules when hardware handshaking is enabled. The

module:

• does not transmit until CTS (Clear to Send) becomes active, and
• examines DSR (Data Set Ready) following the receipt of a character.
If DSR is active, the character is placed in the input queue. If DSR is inactive, the
character is assumed to be noise and is discarded.
DTE and DCE Overview
IMPORTANT
DTE - Data Terminal Equipment
The serial ports are configured as 9-pin Data Terminal Equipment (DTE), as are
most terminals or computer ports.
DTE 9 Signal
Pinout Description
Pin #
1 NC-No Connection
2 RXD-Received Data
3 TXD-Transmitted Data
4 DTR-Data Terminal Ready
5 COM-Signal Common
6 DSR-Data Set Ready
7 RTS-Request to Send
8 CTS-Clear to Send
9 NC-No Connection
Publication 1746-IN009B-EN-P - August 2005
You need to know whether the device connecting to the module
has a DTE or DCE interface. Figures 8 through 12, starting on
page 16, are provided to help you make the appropriate
connection.
Signal from DTE DTE 25
Perspective Pinout
Input
Input
Output
Output
Shared
Input
Output
Input
Input
Signal
Description
Pin #
8 CD-Carrier Detect
3
2
20
7
6
4
5
22 RI-Ring Indicator