User manual

Publication ENET-UM001I-EN-P - January 2010 115
Interlocking and Data Transfer Between Controllers Chapter 7
Communicate with PLC-5 or
SLC Processors
If the message is to a PLC-5 or SLC 500 processor and it reads or writes
integers (not REALs), use a buffer of INTs in the message. Remember that:
• Logix5000 controllers execute more efficiently and use less memory
when working with 32-bit integers (DINTs).
• PLC-5 and SLC 500 processors require 16-bit integers.
• Messages require an INT buffer.
• Data can be moved into or out of the buffer as needed.
Converting between INTs and DINTs
If the message is to a device that uses 16-bit integers, such as a PLC-5 or SLC
500 controller, and it transfers integers (not REALs), use a buffer of INTs in
the message and DINTs throughout the project. This increases the efficiency
of your project.
1. The Message (MSG) instruction reads 16-
bit integers (INTs) from the
device and stores them in a temporary array of INTs.
2. An File Arith/Logical (FAL) instruction converts the INTs to DINTs
for u
se by other instructions in your project.
1. An FAL instruction converts the DINT
s from the Logix5000 controller
to INTs.
2. The MSG instruction writes the INTs from the temporary array to the
device
.
Read 16-Bit Integers Data From
the Device
Buffer of INTs DINTs For Use In
the Project
Word 1
INT_Buffer[0] DINT_Array[0]
Word 2
INT_Buffer[1] DINT_Array[1]
Word 3
INT_Buffer[2] DINT_Array[2]
1
2
Write 16-Bit Integers DINTs From the
Project
Buffer of INTs Data For the
Device
DINT_Array[0] INT_Buffer[0]
Word 1
DINT_Array[1] INT_Buffer[1]
Word 2
DINT_Array[2] INT_Buffer[2]
Word 3
1
2