GFK-0467K Chapter 4 Series 90-30/20/Micro Instructions Set 4-9
4
Section 2: Timers and Counters
This section explains how to use on-delay and stopwatch-type timers, up counters, and down
counters. The data associated with these functions is retentive through power cycles.
Abbreviation Function Page
ONDTR Retentive On-Delay Timer 4-11
TMR Simple On-Delay Timer 4-14
OFDT Off-Delay Timer 4-17
UPCTR Up Counter 4-20
DNCTR Down Counter 4-22

Function Block Data Required for Timers and Counters

Each timer or counter uses three words (registers) of %R memory to store the following
information:
current value (CV) word 1
preset value (PV) word 2
control word word 3
When you enter a timer or counter, you must enter a beginning address for these three words
(registers) directly below the graphic representing the function. For example:
(enable) *|ONDTR|*(Q)
time
(reset) - R
(preset value) - PV
(address) - Enter the beginning address here. here.
- ONDTR -
Note
Do not use consecutive registers for the 3 word timer/counter blocks. Logicmaster
does not check or warn you if register blocks overlap. Timers and counters will
not work if you place the current value of a block on top of the preset for the
previous block.