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Using a shared COM port for an External Modem on Microsoft Virtual Server 2005

We are running Microsoft Virtual Server 2005. We are trying to run an external USR Modem off of the external COM1 port via a seriel cable.

The modem works fine when we go to use it through the physical server. The problem is when we go to map the virtual com port in the virtual server, the port maps but it won't auto detect the attached modem. I can manual create and install the modem. I can send commands to the modem, but when I try to dial with the modem it gives me en error stating the device is not available, attached or functioning properly. (Error 680 I believe, I'm stuck waiting for a down time to reboot due to to many hardware changed right now, so I can't pull up the exact error, sorry :)  )

Also, once the com port is shared to the virtual server, the physical server will give the same error when trying to access the modem. I followed the instructions on technet and msdn regarding sharing of com ports with MS Virtual Server but to no avail. I was wondering if anyone has gotten this to work and how it was done. Thank you.

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SafetyNet-TC
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SafetyNet-TC
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SafetyNet-TCAuthor Commented:
More points for question..

anyone... anyone... We are trying to test this, and I've been all over technet, msdn, and here and can't find where anyone has posted a working installation instruction for using a seriel com modem off of a virtual server. It's supposed to be possible. I've tried three physical boxes on multiple Virtual Servers with no luck. All the same, it just errors out.
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ChiefITCommented:
I would like to help and use com ports for my scientific instruments all the time. This one may be a bit beyond me without physically being there. Maybe I can give you some things I have seen and we can go from there.

The autodetect feature will only cycle through baud rates. It doesn't change the stop bits, flow control, ect... You may have your communications parameters close enought to communicate, as you indicated above. You may wish to contact the manufacturer of the modem and find out what the communications perameters are.

On another note: Hyperterm and other terminal services sometimes seize the port. You may need to find out a way to reset the port.

If you can communicate, it sounds like your wiring is correct for that modem. Usually you only need 3 wires to communicate with a serial device. Those would be on pins 2,3, and 5 of a serial cable. 2=transmit, 3=recv, 5=common. Some devices require aditional wires. If you are using the cable that came with the modem, then no worries.


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SafetyNet-TCAuthor Commented:
Cabling is not an issue, it's an rs232 serial cable, I can use it from my laptop with out issue. The communications settings are fine, Default modem settings (9600,1,8,hardware).

It could be an issue with the physical box and the virtual server not sharing the resource correctly, and I suspect that is where the problem is. I have tried removing the device from both servers and then installing only on the virtual with no luck, I have tried different servers, I have reinstalled the com ports, just can't get it to work.
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ChiefITCommented:
Some folks disable the com ports in BIOS. Have you checked that?
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SafetyNet-TCAuthor Commented:
It works no problem before sharing to virtual, and I can query the modem from the virtual server but can't dial out.
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ChiefITCommented:
Oh yah, you did mention that.

Is this a 64 bit server?

This could be an incompatible driver.
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SafetyNet-TCAuthor Commented:
Sorry, forgot to mention, tried on both x64 and x32 servers. I know it has to do with how the com port is shared. I'm going to be checking some more forums (technet, msdn public) later
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ChiefITCommented:
Sorry for the long delay in response. Maybe this link will help. If you are trying to access com ports over a terminal service, it needs redirection. Here is a link to help troubleshoot redirection.

http://support.citrix.com/article/CTX384590
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SafetyNet-TCAuthor Commented:
It turns out you need to use the generic 56k modem driver.
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