Communicating using USB port

We are writing an application that runs on the Pocket PC which needs to
configure a Process controller that has a RS-485 interface. We have a USB to
RS-485 converter. From an iPAQ pocket PC we are connecting the ActiveSync
USB cable to the USB-to-RS485 converter. From the Device manager I am able
to see that there is a serial over USB driver named COM9:

I opened the COM9: port using the CreateFile API and tried to write to the
port. It gives me an error saying "Parameter is Incorrect" . While I do the
same with "COM2:" which has the IR mapped on to it, the data is being send
successfully.

Please help me as to how to communicate using the cradle communication port.

Dick
Sat Sep 06 13:10:53 CDT 2003

Hi,

The USB port on a Pocket PC is not a host port. It cannot be used with a
USB to serial port converter.

Hello,

You have two options, both involve using a standard RS-232 serial port.

Some Pocket PCs (not all) have a built-in serial port. You can use this
with a ActiveSync serial cable, and a null-modem adapter. (This will be
Com1.)

Other PPCs may require that you use a Compact Flash serial port card. I use
a Socket Communications (www.socketcom.com) adapter.

In either case, you would then have to connect in-line, a RS-232 to RS-485
adapter. There are a number of manufacturers of these devices. You can
find links to several on my homepage.

--
Richard Grier (Microsoft Visual Basic MVP)

See www.hardandsoftware.net for contact information.

Author of Visual Basic Programmer's Guide to Serial Communications, 3rd
Edition ISBN 1-890422-27-4 (391 pages) published February 2002.