Winfax issue on USB MODEM driver

NTDEV
1

Can anyone help me?

I write a USB modem driver. It is ok of using it to access internet. But when using winfax to receiving fax, winfax don’t send the dc2(0x12) after receiving the “…CONNECT” string . If I using Ventafa to receive fax, Venta fax sent the dc2.

Why ?

Thank you very much.

2

Huaping Jiang wrote:

I write a USB modem driver. It is ok of using it to access internet.
But when using winfax to receiving fax, winfax don’t send the
dc2(0x12) after receiving the “…CONNECT” string . If I using
Ventafa to receive fax, Venta fax sent the dc2.

I’ll ask again, are you implementing IOCTL_SERIAL_IMMEDIATE_CHAR?

3

Hi Chris Aseltine

4

Hi Chris Aseltine
thank you very much for your answer.
I haven’t implemented the IOCTL_SERIAL_IMMEDIATE_CHAR.But is there any relation between winfax’s dc2(0x12) and Ioctl_serial_immediate_char?

Thanks again.

huaping jiang

5

Dear Chris Aseltine
this issue is fixed using your method, adding the processing of IOCTL_SERIAL_IMMEDIATE_CHAR.

thank you very much.

I’m really appreciate for your help.

thank you again.

huaping jiang

6

huaping jiang wrote:

this issue is fixed using your method, adding the processing of
IOCTL_SERIAL_IMMEDIATE_CHAR.

See? Toldja… :slight_smile:

The hardest lesson I learned from doing a USB modem driver is that none of the serial spec is really optional, even if it doesn’t apply to your hardware.

For example, I doubt your driver is set up with a transmit queue, but you still needed to implement IMMEDIATE_CHAR (and I’ll give you fair warning that someone eventually will want to use the EV_TXEMPTY event, so spare yourself the pain and implement it now while you can…)