Reading from COM port for 2 days

Question

naser moravej 2022-11-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1864423-reading-from-com-port-for-2-days

回答： chrisw23 2022-11-28

Hello everyone,

I have an instrument which continuously sends data over serial port (I use an USB to TTL) with baud rate 460800. Currently I can capture its data for about 6 hours (the target PC has 4GB of ram). This period of time doesn't satisfy my requirement. I'm tring to read from serial port for 2 days (or more). Perhaps this limition is because of the amount of system's ram. Is there any way to save data directly to the hard disk to eliminate this limition?

This is my code. The code suppose to infinitely read from serial port util the USB to TTL get upluged.

    packet_length = 816;
    numT = 100000
    rawData1D = zeros(1, numT * packet_length);
    s = serial('COM22','BaudRate',460800,'timeout', 10);
    s.InputBufferSize = 242400000;
    fopen(s);
    C = 1;
    a = 0;
    while 1
        a = fread(s,packet_length);
        
        if size(a,1) < packet_length
            break;
        end
        
        rawData1D(packet_length * C + 1: packet_length * (C + 1)) = a;
        
        C = C + 1
       
    end
    fclose(s);
    
    

Thanks for your suggestion.

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Answer 1

chrisw23 2022-11-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1864423-reading-from-com-port-for-2-days#answer_1114228

I suggest to use event based communication. Reading a fixed packet length may lead to a buffer over-/underrun due to asynchronous write and read operations.

read this Serial Events