Timer – IL

The IEC 61131 standart offers a definition of Timers. PLC3000 integrates only TON timers that can be set by defining the time base %Ti.TB, and the preset value %Ti.PV. The timer is triggered by activating the input %Ti.IN, and the output %Ti.Q goes to 1 when the current timer value reaches the preset value.

The time bases %Ti.TB that can be declared are: 10, 100 ms; 1, 10 s; 1 min.

Generation in IL

Let’s consider three timers with different time bases and preset values

LD	%S1
%T0.TB := 100ms
%T1.TB := 1s
%T2.TB := 1min
%T0.PV := 3
%T1.PV := 2
%T2.PV := 1

Illustration with a Grafcet

Let’s consider the following Grafcet

Programming in IL – Transition/Transition with Crossing Bits

* TIMER
LD	%S1
%T0.TB := 100ms
%T0.PV := 3
* INIT
LD	%S2
S	%M0
R	%M1
* TRANSITIONS
LD	%M0
AND	%I0
ST	%M10
*
LD	%M1
AND	%T0.Q
ST	%M11
* CROSSING
LD	%M10
S	%M1
R	%M0
*
LD	%M11
S	%M0
R	%M1
* ACTIONS
LD	%M1
ST	%T0.IN