Rockwell Automation Logix5000 Controllers I/O and Tag Data Programming Manual - Manual (Page 40)

Chapter 2 Organize tags
Guidelines for user-defined data types
When you create a user-defined data type, use the following guidelines.
• If you include members that represent I/O devices, you must use logic to
copy the data between the members in the structure and the corresponding
I/O tags. Refer to Address I/O data on page 18 .
• If you include an array as a member, limit the array to a single dimension.
Multi-dimension arrays are not permitted in a user-defined data type.
• When you use the BOOL, SINT, or INT data types, place members that
use the same data type in sequence.
More Efficient Less Efficient
BOOL BOOL
BOOL DINT
BOOL BOOL
DINT DINT
DINT BOOL
Create a user-defined data type
1. In the Controller Organizer, expand Data Types, then right-click User-
Defined and then click New Data Type.
2. In the Data Type Editor, in the Name box, type a name for the user-
defined data type.
3. (optional) In the Description box, type a description for the user-defined
data type.
40 Rockwell Automation Publication 1756-PM004E-EN-P - October 2014