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Rockwell Automation Publication 2097-UM001D-EN-P - November 2012 211
Appendix
D
MicroLogix Explicit Messaging
You can use MicroLogix CIP Generic (MSG) instructions, also known as explicit
messages, to read and write to the drive ID tags over the EtherNet/IP network.
This capability is present in the MicroLogix 1100 Series B and MicroLogix 1400
controllers. You can write to read/write (R/W) ID tags, however, read (R)
ID tags are read-only. For the complete list of Kinetix 300 ID tags, see
Appendix C .
Explicit Messaging Data
Types
ID tags are designated as either DINT, REAL, or string data types. The
MicroLogix controller uses long file elements, such as L12:0 for DINT data
types, floating point file elements, such as F13:0, for Real data types, and string
file elements, such as ST14:0 for string data types.
The attribute value is used to designate the data format as DINT, REAL, string,
and the memory location as volatile or nonvolatile.
Table 81 - Data Type Attributes
Explicit messaging lets DINT data types to be read into and written from long
file elements directly and Real data types to be read into and written from
floating point file elements directly. String data types must be read into integer
file elements, such as N11:0, by the MSG instruction and then copied into a
string file element. Similarly strings must be copied into integer file elements first
before being written by the MSG instruction.
Topic Page
Explicit Messaging Data Types 211
Explicit Messaging Data Type Examples 212
Attribute Format Memory Stored In
0 DINT Volatile
1 DINT Nonvolatile
2 REAL Volatile
3 REAL Nonvolatile
4 String Volatile
5 String Nonvolatile