Interfacing legacy serial applications with new USB devices

Greetings,

I have numerous legacy applications that communicate with hardware via
RS232. Now, the hardware is USB interface only. Do I have to write a
device driver for the USB hardware that enumerates itself as a virtual
serial port on the PC? Is there a 3rd party software solution that
would help? I don't believe there's a simple hardware solution such
as a cable that will convert the USB hardware to serial (I've seen
cables for the other way around ... serial hardware to USB). Any
ideas or suggestions would be much appreciated.

Thank you in advance,

Scott Ballard

 

In general, cross-posting is considered a no-no.

If the hardware presents itself as COMx, why would you have to change
anything other than the port the applications talk to?

Rob

 

Yes. Furthermore, the driver is going to be specific to the USB device.
It's unlikely that you would find a generic solution to the problem.

 

Not that I ever knew.

His point was that his device does NOT look like a COM port.

 

You've never heard people complain of cross-posting before?

Ah yes, misread that bit.

Rob

 

Hi Rob,

Thanks for the quick reply. The hardware doesn't present itself as
anything as no device drivers have been written yet! I guess I just
wanted to confirm the best way to do it before I spend time
implementing a solution. It seems to me the best way is to write a
device driver for the hardware so that it presents itself as COMx. I
just wanted to make sure there's no other way than to write the device
driver.

As for cross-posting, I usually limit myself to a maximum of three
groups. No one's complained before so I apologize if I've violated
any etiquette specific to this group.

Regards,

Scott Ballard

 

I misread your first post. Since it seems that some driver will have to be
written, having it emulate a COM port is an option.

No worries there, it appears you haven't. The members of some other servers
I've perused are downright militant about it. Not so here though.

Cheers,
Rob

 

Hi, read the post about usbser.sys on 21/09 by holi, that is about the
same. On the atmel website, look for application note that needs file
c5131-usb-cdc-1_0_1.zip implement the cdc driver in the usb controller in
your device. Next use the inf files used in the same application note.

It is time saving to say the least. It will present itself as a comm port
on windows.

Worked for me!

Revo

 

Several vendors have frameworks for Virtual Serial Port (VSP) creation
which more or less solve the problem of writing a VSP from the ground
up. I suggest using google keywords "Virtual Serial Port" and see
what rises. Vendor support and robust reference designs SDK's and
tools are critical for these implementations, and your mileage will
vary depending upon the vendor's commitment.

Regards,

Sherman Couch
Consulting Software Engineer
Constellation Data Systems, Inc.

 

You might want to look at a serial port emulation driver available from
http://www.mixw.net/related.htm#tncemu,

I'm not sure if the driver is written as WDM (likely not), but I've
installed and used it. Experiences may vary.

Cheers,
Rob