Sharing serial port on host

[robatwork]

I have a brand new PC running Windows 7 Pro with latest VB setup.
I put a serial card into it which is showing as COM3.

I have now installed 2 x virtual PCs running Windows 7 too. I can tick the Enable serial port box on VM1, put in port number COM3, choose Port Mode Host Device, Port/File Path: COM3. This can now see and use COM3 on the host.

However on VM2 I can't choose Port Number COM3 when I enable the serial ports - I get an error.
So can I not share the serial port between 2 or more VMs?

thanks

[mpack]

UART and LPT ports can't be shared. Only one app (e.g. one VM) at a time can use it. The standards are very old and were designed for point to point comms only.