Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 106)

Preface MicroLogix 1000 Programmable Controllers User Manual
6–8
Timer Instructions Overview
Each timer address is made of a 3-word element. Word 0 is the control word, word 1
stores the preset value, and word 2 stores the accumulated value.
EN TT DN Internal Use
15 14 13
Preset Value
Accumulator Value
EN = Timer Enable Bit
TT = Timer Timing Bit
DN = Timer Done Bit
Word 0
Word 1
Word 2
Entering Parameters
Accumulator Value (ACC)
This is the time elapsed since the timer was last reset. When enabled, the timer
updates this continually.
Preset Value (PRE)
Specifies the value which the timer must reach before the controller sets the done
bit. When the accumulated value becomes equal to or greater than the preset value,
the done bit is set. You can use this bit to control an output device.
Preset and accumulated values for timers range from 0 to +32,767. If a timer preset
or accumulated value is a negative number, a runtime error occurs.
Timebase
The timebase determines the duration of each timebase interval. The timebase is
selectable as 0.01 (10 ms) second or 1.0 second.