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Configuring COM ports

Configuring COM ports

You can use a virtual machine's COM port settings to enable communications between the virtual machine and a device or file. You can configure one or two COM ports for a virtual machine. For each COM port, you can use one of the settings described in the following table.

 

Setting Description

None

Select this options to configure the virtual machine as though no device is connected to the COM port. This is the default setting.

Physical serial port

Select this option to specify the use of a serial port on the physical computer for input and output on the virtual machine. Virtual machines can only be configured to use COM ports 1 through 4 of the physical computer.

Wait for modem command to open port

Select this option if you want the serial port on the physical computer to be captured when a program running on the virtual machine attempts to access the COM port. This option causes Virtual Server to wait for an AT modem command to be sent for the port. If the program using the COM port times out after capturing the port, the port is released to the host operating system.

Clear this option if you want the virtual machine to attempt to capture the serial port on the physical computer when the virtual machine starts. If the serial port is already captured, the virtual machine cannot capture it. If the virtual machine captures the serial port, the serial port is not released to the host operating system until the virtual machine is shut down.

Named pipe

Select this option to connect the virtual serial port to a Windows named pipe on the host operating system or between virtual machines on the same virtual network. A named pipe is a portion of memory that can be used by one process to pass information to a second local process, so that the output of one is the input of the other. An example of a local named pipe path could be \\.\pipe\my pipe name.

Named pipes can be used to create a virtual null modem cable between two virtual machines, or between a virtual machine and a debugging program on the host operating system that supports the use of named pipes. By connecting two virtual serial ports to the same named pipe, you can create a virtual null modem cable connection. Named pipes are useful for debugging or for any program that requires a null modem connection.

Text file

Select this option to send COM port output from the virtual machine to a text file. You can specify a text file location on any valid disk drive on the physical computer.

For instructions, see Configure a COM port.

noteNote
A device attached to the COM port can be used by only one virtual machine at a time. The device is not available to other virtual machines or to the host operating system until the virtual machine is shut down.
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