MATLAB Programming

10 Scheduling Program Execution with Timers
Executing a Timer Callback Function Multiple Times
The timer object supports three multiple-execution modes:
• 'fixedRate'
• 'fixedDelay'
• 'fixedSpacing'
In many ways, these execution modes operate the same:
• The TasksToExecute property specifies the number of times you want the
timer to execute the timer callback function (TimerFcn).
• The Period property specifies the amount of time between executions of
the timer callback function.
• The BusyMode property specifies how the timer object handles queuing of
the timer callback function when the previous execution of the callback
function has not completed. See “Handling Callback Function Queuing
Conflicts” on page 10-21 for more information.
The execution modes differ only in where they start measuring the time
period between executions.Thefollowingtable describes these differences.
Execution
Mode
'fixedRate'
'fixedDelay'
'fixedSpacing'
Description
Time period between executions beginsimmediatelyafter
the timer callback function is added to the MATLAB
execution queue.
Time period between executions begins when the timer
function callback actually starts executing, after any time
lag due to delays in the MATLAB execution queue.
Time period between executions begins when the timer
callback function finishes executing.
The following figure illustrates the difference between these modes. Note that
the amount of time between executions (specified by the Period property)
remains the same. Only the point at which execution begins is different.
10-20