Tweak to get timeout in serial read/write less than 1 second

Question

Marko Gulin 2019-12-22

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497753-tweak-to-get-timeout-in-serial-read-write-less-than-1-second

编辑： Marko Gulin 2019-12-22

Hi all,

It seems that Timeuot property in serial object, although specified as double, is rounded upwards full seconds.

Is there a tweak to have it less than 1 second? I really don't understand why they decided to implement the Timeout property like that in the first place.

I have an idea to use a timer in single shot execution mode. Although it works, I'm not sure if it is recommended to have it like that.

Here is my proposal, please let me know what you think:

% obj.flag is logical flag
% obj.ser is serial port object
function readTimeout(obj)
%READTIMEOUT
    
    % Timeout has occurred
    obj.flag = true;
    
end
function msg = read(obj, noOfBytes, timeout)
%READ
    
    % Create timeout timer
    tmr = timer(                                      ...
        'TimerFcn', @(objj,event) obj.readTimeout(),  ...
        'ExecutionMode', 'singleShot',                ...
        'StartDelay', timeout                         ...
    );
    
    % Start timeout timer
    obj.flag = false;
    start(tmr);
    
    % Wait for bytes
    while (obj.ser.BytesAvailable < noOfBytes)
        if obj.flag == true
            error('serial:timeout', 'Timeout exception.');
        end
    end
    
    % Read available bytes
    msg = fread(obj.ser, noOfBytes, 'uint8');
    
end