Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 136)

Publication AG-UM008C-EN-P - February 2005
3-68 Configuring MicroLogix 1100/1200/1500 Controllers
Information for Creating Your Own Application
Controller Receives Communications Packet
Table 3.14 Command Structure
DST SRC CMD 0f STS TNS FNC A2 Byte Size File No. File Tpe Ele. No. S/Ele. No.
Field Function Description
DST Destination Node
SRC Source Node
CMD Command Code
STS Status Code Set to zero (0)
TNS Transaction Number Always 2 bytes
FNC Function Code
Byte Size Number of bytes to be read Formatted string length (see equation below)
File Number Always set to zero (0)
File Type Must be A5 (hex)
Element Number Queue number Determines the queue to be read (0 to 255)
Sub/Element Number Always set to zero (0)
Table 3.15 Equation
Record Field 1 + Record Field 2 + Record Field 3 … + Record Field 7 = Formatted
String Length
Table 3.16 Record Field Sizes
Data Type Maximum Size
Word 7 bytes (characters)
Long Word 12 bytes (characters)
Date Field 11 bytes (characters)
Time Field 9 bytes (characters)
TIP
The formatted string length cannot exceed 80 bytes
in length.
TIP
The last byte will be a zero value representing the
terminator character.