Hardware handshaking -10, Hardware handshaking – Rockwell Automation 1746-BAS-T SLC 500 Basic Basic-T Modules User Manual
Page 44
Publication 1746-UM004B-EN-P - December 2005
3-10 Install and Wire Your Module
(1)
In RS-423 mode, these pins are still connected to their RS-422 loads. Do not use these pins in RS-423 mode.
(2)
In RS-422 and RS-485 modes these pins are connected to their RS-423 drivers and receivers. Do not use these
pins in either RS-422 or RS-485 mode.
(3)
In RS-485 mode, these pins are still connected to their RS-422 receivers. Do not use these pins in RS-485 mode.
Wiring diagrams for the RS-232/423 communication mode are shown
starting on page 3-12.
Hardware Handshaking
The module uses the following rules when hardware handshaking is
enabled. The module:
• does not transmit until CTS becomes active.
• examines DSR following the receipt of a character. If the 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.
Pin
RS-232/423
RS-422
RS-485
IBM AT Standard
RS-232 Signals
1
Note 1
422 TXD -
TRXD -
DCD or CD
2
RXD
422 RXD -
(3)
RXD
3
TXD
(2)
(2)
TXD
4
DTR
(2)
(2)
DTR
5
COMMON
COMMON
COMMON
COMMON
6
DSR
422 RXD +
(3)
DSR
7
RTS
(2)
(2)
RTS
8
CTS
(2)
(2)
CTS
9
(1)
422 TXD +
TRXD +
RI