Allen-Bradley ControlLogix 5570 Reference Manual page 99

If the data type size is different between the two projects, modify the UDT to
produce the same internal data structure.
The following sample UDT illustrates how the 8-byte allocation rule and the
8-byte alignment rule cause a UDT to have another size.
Figure 17 - UDT Sample - Needs Additional Memory Allocation and Alignment
Table 15 illustrates how this data structure maps in a Logix Designer project,
version 26 or earlier. MyLint is split across two 64-bit words, and the total size
is only 32 bytes.
Table 15 - Data Structure for Logix Designer Projects, Version 26 or Earlier
Word Elements
0 LimitA and LimitB
1 Profile (Real [3])
2
3
4 Interlock (Int)
5 MyLint (LINT)
6
7 Speed (REAL)
Rockwell Automation Publication 1756-RM100F-EN-P - October 2018
Standard Application Conversion
Byte Mapping Table
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Chapter 5
64 Bit Boundaries
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