Serial Port not writing

Question

John 2014-8-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/146602-serial-port-not-writing

回答： John 2014-8-7

In Matlab 2014a (on ubuntu 12.04, 64-bit), a serial port that I'm writing to doesn't actually output anything from the FTDI-RS232 cable. As seen by a scope, no bits are being sent, the line remains high. There is no matlab error, and "ValuesSent" increments as it should every time i "transmit". However, TransferStatus remains idle all the time.

I can read data IN to matlab over another serial port just fine, but i'm not trying to write to that one. Thoughts on why a port wouldn't be writing? I have given the appropriate read-write privileges to the port, and if i didn't I'd get a port-open error. No flow control is needed.

 s = serial('/dev/ttyUSB2','BaudRate',115200,'DataBits',8, 'StopBits', 1);
 fopen(s);
 s.FlowControl = 'none';
 fprintf(s, '%s', 'asbc');
---------------------
get(s) gives:
    ByteOrder = littleEndian
    BytesAvailable = 0
    BytesAvailableFcn = 
    BytesAvailableFcnCount = 48
    BytesAvailableFcnMode = terminator
    BytesToOutput = 0
    ErrorFcn = 
    InputBufferSize = 512
    Name = Serial-/dev/ttyUSB2
    ObjectVisibility = on
    OutputBufferSize = 512
    OutputEmptyFcn = 
    RecordDetail = compact
    RecordMode = overwrite
    RecordName = record.txt
    RecordStatus = off
    Status = open
    Tag = 
    Timeout = 1
    TimerFcn = 
    TimerPeriod = 1
    TransferStatus = idle
    Type = serial
    UserData = []
    ValuesReceived = 0
    ValuesSent = 260
    SERIAL specific properties:
    BaudRate = 115200
    BreakInterruptFcn = 
    DataBits = 8
    DataTerminalReady = on
    FlowControl = none
    Parity = none
    PinStatus = [1x1 struct]
    PinStatusFcn = 
    Port = /dev/ttyUSB2
    ReadAsyncMode = continuous
    RequestToSend = on
    StopBits = 1
    Terminator = CR/LF