Mark,
Thanks for your response.
I have understood that external operating system is necessary for flow control.
However it is hard to change current project at this time.
Then I have one more question.
Is there any way to change CDC baud rate ?
I found following codes in virtual_com.h and changed 115200 to 2400, but unfortunately it affected nothing.
/* Currently configured line coding */
#define LINE_CODING_SIZE (0x07)
#define LINE_CODING_DTERATE (115200)
#define LINE_CODING_CHARFORMAT (0x00)
#define LINE_CODING_PARITYTYPE (0x00)
#define LINE_CODING_DATABITS (0x08)
Regards,
Shuichi