RAS null modem connection: Unavailable Device COM1

  • Thread starter Thread starter Mark K Vallevand
  • Start date Start date
M

Mark K Vallevand

I can't get a network connection over a null modem cable. I think I've
included all the necessary components. Obviously I've missed something.
Why would I get Unavailable Device COM1? Its there. It works.

Anyone have a list of components needed for a network connection over a null
modem cable?
 
COM1 works in my Windows XP embedded. It needed the components Class
Installer - Ports (COM & LPT) und Communications Port. Due to some
fact I had to disable COM3 and COM4.
What is the output of your device manager?

Regards
Susanne Stoehr
 
I have both of those components. My device manager shows both available com
ports as normal. I can use programs to open a com port and send/recv data.
The problem is that when I create network connections, the com ports
assignments are OK, but always reported as unavailable. Its like there is
some missing component which associates physical com ports with those
available for dialup networking.

Anyone have any ideas?

Can someone send me their list of components in a image that successfully
does serial port networking? A build log would be fine.
 
More research indicates that there might be a permissions problem with the
com port. When I try to set the advanced properties of the com port, I get
a message about needing write permission in the registry.

Anyone ever seen that one?
 
The exact message is

You must have write privileges in the registry for this
device in order to modify the device's advanced settings.A google search
indicates that other have had this problem. The solution was to change the
permissions in the registry for
hklm\system\CurrentControlSet\Enum\Root\*PNP0501. I did that, giving
everyone full access. Its not better.
 
OK. It turns out there was both a *PNP0501 and a *PNP0500 in the registry.
Setting the permissions on the other one allowed me to set advanced
properties for the serial port. However, I still can't get a networking
connection over the serial port. The device unavailable for networking.

Argh. What can I be missing? Suggestions are very welcome.
 
Dear Mark.
I faced the same problem and I'd like to know if you have managed to sort it
out?
I am looking forward to hearing from you soon.
Thanks & best regards,
Alexander
 
It has not been sorted out. However, we're getting help directly from
Microsoft. Maybe there will be an answer someday.
 
Dear Mark.

Thank you very much for your information. If you have any news from
MicroSoft
concerning this matter, please let me know.

Best regards,
Alex
 
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