Regarding USB-to-serial device driver

Raju Rameshwar Uprade
2010-09-28T09:22:13Z

Hello Greg,

I am using pl2303.c ( USB to serial device driver ) to communicate to various
devices connected in parallel using RS-485 interface card.

I am now able to separate the Address byte and data bytes.Driver send the Address byte
properly but when it tries to send the data bytes following error occurs,

pl2303_mcm ttyUSB0: pl2303_write - failed submitting write urb, error -22.

I have also attached the kernel log.

/home/teleset/Desktop/USB-Serial/pl2303_mcm.c: pl2303_write before any thing - port 0, 9
bytes
/home/teleset/Desktop/USB-Serial/pl2303_mcm.c: set_control_lines - value = 3, retval = 0

Data in The BUF 0 is -----> 02

Data in The BUF 1 is -----> 08

Data in The BUF 2 is -----> 00

Data in The BUF 3 is -----> 00

Data in The BUF 4 is -----> 00

Data in The BUF 5 is -----> 00

Data in The BUF 6 is -----> 00

Data in The BUF 7 is -----> 00

Data in The BUF 8 is -----> f8
pl2303_mcm ttyUSB0: pl2303_write - length = 1, data = 02
/home/teleset/Desktop/USB-Serial/pl2303_mcm.c: After the first urb submission count = 9
and length = 8
pl2303_mcm ttyUSB0: pl2303_write - length = 8, data = 08 00 00 00 00 00 00 f8
pl2303_mcm ttyUSB0: pl2303_write - failed submitting write urb, error -22
/home/teleset/Desktop/USB-Serial/pl2303_mcm.c: pl2303_write_bulk_callback - port 0
/home/teleset/Desktop/USB-Serial/pl2303_mcm.c: set_control_lines - value = 0, retval = 0

Kindly help me.

Raj.