MATLAB: Timer to send a new message

simulinktimertrigger

Hi all

I have a system with receiver and a triggered sender. When the receiver receives a new message it will trig the sender to send the next message.So if the message lost in their way to the receiver the system will hang forever.

I need a timer that wait the message for a specific period ( 1 sec ) , if no new message received the sender will triggered to send next message. of course this timer reset when receiver has a new message.

My receiver has a trigger out port that switches between 1 and -1

Best Answer

I would probably use a resettable integrator for this task. Feed the integrator a constant value of '1', that way it will act as a timer. If the timer reaches a defined value (1 sec) send a message (then reset the integrator). If you receive a message, send a new one, and just reset the integrator to zero and it will begin counting up again.

Of course - there is always the option of using Stateflow for such a task.

Related Solutions

MATLAB: How to use ‘Timer’ function to send ROS messages

You can use MATLAB timers in this way :

% Create a timer object
 t=timer;

Set execution mode of the timer object to fixedRate, fixedDelay or fixedSpacing to execute your call back repeatedly

 set(t,'executionMode','fixedRate');

Specify the function handle or the command you want to be executed. In your case, for sending messages over a ROS topic , use send :

set(t,'TimerFcn','send(pub,msg)');

Set the frequency or period(in seconds),at which the timer callback function is called

% To publish the message at a rate of 50 times per second 
set(t,'Period', 0.02);
% Start the timer
start(t);

ROS message msg is then sent periodically(every 0.02 seconds). To stop the timer:

stop(t);

Delete the timer object after usage

delete(t);

MATLAB: How to have a Triggered Subsystem execute at every rising edge of a stair function in Simulink 7.6 (R2010b)

A Triggered Subsystem will execute on a rising edge when the value before the edge is nonpositive.

Instead of sending the stair signal directly to the subsystem, add a Detect Increase block between the signal and the trigger port. The Detect Increase block compares the signal to its value in the previous time step using a Unit Delay and a Relational Operator block.

Please see the attached model which demonstrates this.

Best Answer

Related Solutions

MATLAB: How to use ‘Timer’ function to send ROS messages

MATLAB: How to have a Triggered Subsystem execute at every rising edge of a stair function in Simulink 7.6 (R2010b)

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