MATLAB: How to get the time of a running event

access timedaq sessionevent

I created a daq session to monitor the voltage change, and I need to get the time of the event at some timepoint. I tried listener, but it greatly slows down the system. What I need is the time of the event at the point that an internal trigger starts. Is there anyway I can access the immediate time of the running event?

Thanks

Best Answer

Hi,

You can use the tic-toc mechanism to start timing when the trigger is issued, and stop at the point where you want to measure the running time. toc - tic will give you the running time.

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MATLAB: Using a timer to execute a function

A simple timer:

   t = timer('BusyMode', 'Drop', ...
            'ExecutionMode', 'fixedDelay', ...
            'StartFcn', [], ...
            'TimerFcn', @(obj, evd) disp('hallo'), ...
            'StopFcn', [], ...
            'Period', 2);

Issue start(t) to start the timer and stop(t) to stop it.

This timer executes the timer function @(obj, evd) disp('hallo') every 2 seconds. If the execution of the TimerFcn has not completed before the next execution, then the timer will Drop the next execution.

You can create your own callback for your TimerFcn.

At the end issue

delete(t)

MATLAB: Anyone listening for a particular event

@Joan, This is an interesting problem! I don't know what the ideal solution is, but maybe you could create three classes: subscriber, contract and broker. The broker class would manage the other two. It would behave something like this:

Maintain a structure marketFeeds with dynamic fields feedname. Each field has two subfields: subscriberHandle and listenerHandle.
Input handle to new contract ( broker.addContract(contractHandle) ).

For each feed name, see if it is one of the field names in marketFeeds.

If it exists, add contractHandle to list of handles maintained by the corresponding listener ( i.e., listenerHandle.addContract(marketFeeds.feedName.contractHandle)).

If it doesn't exist, add a new subscriber object and a listener for that object. Give the handle of the contract to the listener.

When a listener is told of a change in the market feed, it calls each of the handles with some command like contractHandle.reactToMarketChange(feedName,NewValue).

When the contract is terminated, send its handle to broker.deleteContract, which then does all the necessary actions on marketFeeds.

Best Answer

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MATLAB: Using a timer to execute a function

MATLAB: Anyone listening for a particular event

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