Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 132)

Publication AG-UM008C-EN-P - February 2005
3-64 Configuring MicroLogix 1100/1200/1500 Controllers
DLG - Data Log Instruction
The DLG instruction triggers the saving of a record. The DLG
instruction has one operand:
Queue Number - Specifies which data log queue captures a record.
The DLG instruction only captures data on a false-to-true rung
transition. The DLG rung must be reset (scanned false) before it will
capture data again. Never place the DLG instruction alone on a rung.
It should always have preceding logic, as shown below:
Data Log Status File
There is a Data Log Status (DLS) file element for each Data Log
Queue. The DLS file does not exist until a data log queue has been
configured.
The Data Log Status file has 3-word elements. Word 0 is addressable
by bit only through ladder logic. Words 1 and 2 are addressable by
word and/or bit through ladder logic.
IMPORTANT
You must configure a data log queue before
programming a DLG instruction into your ladder
program.
Data Log
queue number
0
DLG