COM Port in Virtual Machine - Extended guide for Hyper-V, VMware, VirtualBox

Using COM Ports on Virtual Machines

Guest Virtual Machines can benefit from communication with devices or host applications via serial ports in many usage scenarios. USB to COM devices can be attached directly to a virtual machine. Native COM devices are only accessible to a Virtual Machine if it has been connected to the host computer.

VMs use bridges to forward serial port data to guest machines. When a VM is connected to a particular COM port, it becomes unavailable to the host machine. Establishing a pair of virtual serial ports enables data transfers between host and guest applications.

Setting Bridge Ports Inside Virtual Machines

A setting within virtual machines enables users to establish a bridge between serial ports on the host and guest machine as an alternative to creating a new COM port for connectivity. Windows hosts offer legacy for COM ports numbered 1 through 9. Full device naming conventions are required for higher numbered ports, for example, \.\COM10.

The bridge provides connection mode options to support use with various types of applications. Uses include controlling serial devices from a guest operating system and exchanging data between two real or virtual machines to troubleshoot COM ports and attached equipment.

The connection modes available are:

• • File
• • Pipe
• • TCP

Accessing Serial Ports in VirtualBox,
Hyper-V, and VMware

Serial ports can be accessed in the following virtual environments.

• • VirtualBox - When a VirtualBox serial port is enabled, the guest OS obtains access to a UART device for data transmission. Specific configuration details depend on the host OS in use.
• • Hyper-V - The Hyper-V Manager does not display serial ports by default. COM port connectivity can be established with additional configuration, allowing VMs to implement serial port passthrough functionality.
• • VMware - VMware VMs can create up to four virtual serial ports. Each port facilitates communication with physical serial ports on the host machine and can output data to named pipes or files.

After configuration is complete, the virtual machine will obtain full functionality over the connected physical COM port and any attached devices.

Conclusion

This guide illustrates how you can manage serial ports in various types of virtual environments. The options and steps discussed will help you implement efficient and effective communication between serial devices and virtual machines. VM users can enjoy improved productivity and superior utilization of peripheral devices.