User manual

Rockwell Automation Publication 1769-UM011I-EN-P - February 2013 67
Communicate over Networks Chapter 4
Convert Data to or from ASCII Characters
Modbus Support
To use Logix5000 controllers on Modbus, connect the controllers through the
serial port and execute specific ladder logic routines.
A sample controller project is available with RSLogix 5000 Enterprise
programming software.
Broadcast Messages over a Serial Port
You can broadcast messages over a serial port connection from a master controller
to all of its slave controllers by using several communication protocols. Those
protocols are the following:
• DF1 Master
• DF1 Radio Modem
• DF1 Slave
Broadcasting over a serial port is achieved using the ‘message’ tag. Because
messages are sent to receiving controllers, only the ‘write’ type messages can be
used for broadcasting.
The broadcast feature can be set up by using ladder logic programming software
or Structured Text programming software.
The broadcast feature can also be set by modifying the path value of a message tag
in the tag editor.
For this example, Ladder Logic programming software will be used.
Instruction Code Description
STOD Convert the ASCII representation of an integer value to a SINT, INT, DINT, or REAL value
STOR Convert the ASCII representation of a floating-point value to a REAL value
DTOS Convert a SINT, INT, DINT, or REAL value to a string of ASCII characters
RTOS Convert a REAL value to a string of ASCII characters
UPPER Convert the letters in a string of ASCII characters to upper case
LOWER Convert the letters in a string of ASCII characters to lower case