> Wierd. If you enable debugging in the driver: > modprobe pl2303 debug=1 > do you also see the kernel log showing extra data going out to the host? > > What is your userspace program doing? Are you sure you are only writing > 6 bytes? The bulk out should only be writing the actual data in the > buffer, not any more than that. > > Do you have an example userspace code that we can use to test with? > > thanks, > > greg k-h Greg, I am really sorry, that superfluous data was due to user space program.I have modified that.Now I am able to send correct data to the device. 5e and 40 is also going out.I don't know from where it is coming. But I am not getting the response. output of usbmon : ee9e1680 4108443204 C Co:7:003:0 0 0 f6e80c00 4108443237 S Bo:7:003:2 -115 9 = 05080000 00000000 f8 // correct data bytes f6e80c00 4108444202 C Bo:7:003:2 0 9 > ee9e1680 4108448251 S Co:7:003:0 s 21 22 0000 0000 0000 0 ee9e1680 4108449202 C Co:7:003:0 0 0 f6e80700 4108450204 C Bi:7:003:3 0 1 = 00 ee9e1680 4108450546 S Co:7:003:0 s 21 22 0003 0000 0000 0 f6e80900 4108451204 C Ii:7:003:1 0:1 10 = a1200000 00000200 0400 f6e80900 4108451223 S Ii:7:003:1 -115:1 10 < ee9e1680 4108451227 C Co:7:003:0 0 0 f6e80c00 4108451252 S Bo:7:003:2 -115 1 = 5e // don't know from where it is going out f6e80c00 4108452201 C Bo:7:003:2 0 1 > f6e80900 4108453203 C Ii:7:003:1 0:1 10 = a1200000 00000200 0000 f6e80900 4108453221 S Ii:7:003:1 -115:1 10 < ee9e1680 4108456262 S Co:7:003:0 s 21 22 0000 0000 0000 0 ee9e1680 4108457202 C Co:7:003:0 0 0 ee9e1680 4108457225 S Co:7:003:0 s 21 22 0003 0000 0000 0 ee9e1680 4108458201 C Co:7:003:0 0 0 f6e80c00 4108458228 S Bo:7:003:2 -115 1 = 40 // don't know from where it is going out f6e80c00 4108459201 C Bo:7:003:2 0 1 > ee9e1680 4108463235 S Co:7:003:0 s 21 22 0000 0000 0000 0 ee9e1680 4108464204 C Co:7:003:0 0 0 Regards, Raj. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html