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andyste1
Contributor
Contributor

Can't install custom serial port drivers

The host PC has a high speed serial card fitted ("Brainboxes" RS422/485 PCi), plus its respective driver software. In Control Panel -> Device Manager the card's two serial ports appear as "Brainboxes RS422/485 Serial Port (COM8)" and "Brainboxes RS422/485 Serial Port (COM9)". They work fine when I talk to them from the host PC.

I now need to talk to the com ports from the guest machine. I've configured the VM's settings to expose these serial ports, and on the guest machine (Win7) I can see them in Control Panel -> Device Manager, appearing as COM2 and COM3. Unfortunately my software is unable to talk to them, failing to open the serial port. The error message is "The parameter is incorrect", which I believe is due to using a high baud rate (921600) which isn't supported by "vanilla" com ports - hence the need for the Brainboxes driver.

I installed their driver on the guest machine, then tried to update the two com ports (COM2 & COM3) with this driver. However the guest PC crashes at this point with a blue screen of death. Occasionally it will update the driver, but when I restart the PC I get the blue screen again and have to run a Windows repair to rollback the driver installation. Any thoughts?

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wila
Immortal
Immortal

Hi,

The guest never gets direct access to your hosts physical adapters, this includes your special serial ports.

So it is not that strange the special brainboxes drivers for that PCI card can't find the hardware and cause unexpected side effects.

Sorry I have no solution for your problem, but figured it made sense to explain that installing that driver in your guest OS won't help.

--

Wil

| Author of Vimalin. The virtual machine Backup app for VMware Fusion, VMware Workstation and Player |
| More info at vimalin.com | Twitter @wilva
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andyste1
Contributor
Contributor

So if I'm not supposed to install custom drivers, does that mean I won't be able to connect to the serial port at speeds over 115200 (which I believe is the maximum supported by the vanilla Windows driver)?

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RDPetruska
Leadership
Leadership

That is most likely correct, yes.  The guest virtual machine will ONLY see virtualized hardware, NOT the actual hardware... and therefore be unable to use custom drivers.  Therefore, only what is supported by the drivers for the generic/virtual hardware.

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wila
Immortal
Immortal

Hi,

In addition to what Robert says, you can have your VM directly connect to hardware via USB, that would be the only solution I see for you at this moment.

But that would probably require you to buy new hardware and while it works most of the times, there certainly is USB hardware out there that does not connect nicely to a VMware Guest OS.

--

Wil

| Author of Vimalin. The virtual machine Backup app for VMware Fusion, VMware Workstation and Player |
| More info at vimalin.com | Twitter @wilva
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