Why do the functions fread and fwrite take so long to run in Matlab?
1 回表示 (過去 30 日間)
古いコメントを表示
Hi,
I am working on reading and writing data to a piece of hardware from Matlab. Time is an issue for me. I was running a Matlab code that uses the functions fread and fwrite. Using profile report, I saw that these functions take quite a long time. I was wondering what type of stuff are happening under the hood when I call fread and fwrite that are making it take so long. FYI, I am using fread and fwrite to read and write to the COM port.
Thanks in advance, David
2 件のコメント
Walter Roberson
2013 年 6 月 27 日
How much data at a time are you fwrite() ? Is the COM port a USB device emulating a serial port?
採用された回答
Jan
2013 年 6 月 27 日
編集済み: Jan
2013 年 6 月 27 日
Then the speed is not limited by the commands fread and fwrite, but by the COM port setup.
2 件のコメント
Jan
2013 年 6 月 28 日
When you setup the COM port by the command serial to run with 9600 Baud, fread and fwrite are limited by this speed. So please show us the code you use to initialize the serial connection. Seeing the rest of the the code might reveal further problems also, which cannot be guessed blindly.
その他の回答 (1 件)
Ravi
2013 年 6 月 28 日
Why cant you use S-functions & i am reading some 1 lakh data line or values within seconds.... Firstly you send your code & what u have done till now.. Then we can discuss further..
static void mdlOutputs(SimStruct *S, int_T tid) { //get pointer to the block's output signal real_T *y = ssGetOutputPortSignal(S,0);
/*get pointer to array of pointers, where the first element is the address
*of the open file */
void** pwork = ssGetPWork(S);
/*read a floating point number and then the comma delimiter
*store the result in y*/
fscanf(pwork[0],"%f%*c",y);
}
we used such type of code.... So u describe ur code....
3 件のコメント
参考
カテゴリ
Help Center および File Exchange で Periodic Waveform Generation についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!