About CDC and endpoint

[zheng]

Hi,  The following figure 1 shows my system. The first time, I sent a request from the host, and the data written to ep6in from 8051 was correct, but I read ffffffff in the host (as shown in the red box in Figure 2). The second time, I sent the same request from the host again, and I read the correct value in the host (as shown in the basket in Figure 2). Similarly, for subsequent communications, the first reply from fx2lp is ffffff, and the correct information is returned the second time. Would you give me some advice on why?

Fig.1:

Fig.2:

Best regards,

Zheng