Allen-Bradley controllogix 1756-L63, User Manual

Page: 374 / 435

Publication 1756-UM001E-EN-P - August 2002
23-6 Configure Dial-Up Communications
Step 4: Send the Message
A. Enter the following logic:
B. If your message is to a PLC-5
®
or SLC 500
™
controller
and
it
reads or writes integers (not REALs), use a buffer of INTs in the
message.
•
ControlLogix controllers execute more efficiently and use less
memory when working with 32-bit integers (DINTs). Use the
DINT data type for integers whenever possible.
•
PLC-5 and SLC 500 controllers require 16-bit integers.
•
Use an INT buffer in the message and move the data into or
out of the buffer as required.
Serial_port
[1] contains the status of the modem signals. When bit 3 is on (DCD is high), the
modem is receiving the carrier from the remote modem and communication is established. At this
point, the message is sent to the remote controller.
42387
serial_port[1].3
/
message.EN
EN
DN
ER Type - Unconfigured
Message Control
message ...
MSG
Where: Is:
serial_port
array of 19 INTs (INT[19]) that stores the status of the serial
port
message
tag that controls the execution of the message
(MESSAGE data type)