VMware ESXi and vSphere Cluster Management
Add a Virtual Serial Port in VMware Player
Learn how to add and configure a VMware Player virtual serial port for a physical COM port, host file, or named pipe.
A virtual serial port gives the guest operating system a serial interface, usually shown as a COM port. VMware Player redirects data sent through that guest interface to a destination configured on the host: a physical serial port, a host file, or a named pipe.
This is useful for serial modems, legacy printers, embedded-device tools, serial console access, diagnostics, and applications that communicate through a COM or serial interface. The guest sees virtual hardware, while the selected host-side destination handles the redirected serial data.
Capabilities and limits
- A VMware Player virtual machine can have up to four virtual serial or COM ports.
- Each serial port is configured independently, so different ports can use different destinations.
- Supported destinations are a physical serial port on the host, output to a host file, or output to a named pipe.
- Creating the virtual device does not necessarily mean that it is actively connected to its destination. Connection behavior is controlled separately, including by the Connect at power on setting.
Destination options
| Destination type | Where serial data goes | Typical use case | Key configuration items |
|---|---|---|---|
| Physical serial port on host | A real serial interface attached to or built into the host | Using a legacy serial device, modem, printer, or embedded device | Host port selection or Auto detect; connection at power on |
| Output to file | A file stored on the host | Capturing boot messages, console output, logs, or diagnostics | Host path, filename, write permissions, and available disk space |
| Output to named pipe | An operating-system interprocess communication endpoint | Connecting the guest to a host application or another virtual machine | Pipe name, endpoint roles, matching settings, and peer readiness |
Prerequisites
Power off the virtual machine before changing its virtual hardware. A suspended or running virtual machine may not allow hardware changes, and changing hardware while it is active can prevent the intended configuration from being applied.
Also select the intended virtual machine in the VMware Player library. Before starting the wizard, verify that any required host resource is available: a physical serial port must exist and not be occupied, a file destination must be writable, and a named-pipe peer or application must be ready to connect.
| Requirement | Why it matters | How to verify |
|---|---|---|
| Virtual machine is powered off | Virtual hardware settings may be locked while the machine is running | Shut down or power off the guest and confirm it is no longer running |
| Correct virtual machine is selected | Hardware changes apply only to the selected machine | Check the selected entry in the VMware Player library |
| Host serial port availability | A physical port cannot be shared with another host application | Confirm the device is attached and close software using the port |
| Host file path write access | VMware Player must be able to create or write the output file | Check the directory permissions, path, and free disk space |
| Named-pipe peer or application readiness | The other endpoint must open the same communication path | Prepare the host application or second virtual machine and verify compatible settings |
Open the virtual machine hardware settings
- Select the powered-off virtual machine in the VMware Player library.
- Open Player, then choose Manage and Virtual Machine Settings.
- Select the Hardware tab.
- Click Add to start the Add Hardware workflow.
The navigation sequence is Select the virtual machine > Player > Manage > Virtual Machine Settings > Hardware > Add.
Add serial-port hardware
- In the hardware-type list, choose Serial Port.
- Continue to the connection or output-destination step.
- Select and configure the destination type.
- Complete the remaining wizard pages and click Finish.
After the wizard completes, the new serial device should appear in the virtual machine's hardware list.
Configure a physical serial port
- Choose the option to use a physical serial port on the host.
- Select a specific host serial port, or choose Auto detect where that option is available.
- Enable Connect at power on if the guest should attach to the physical port automatically whenever the virtual machine starts.
- Finish the wizard.
Auto detect is convenient when the host has one clear, available serial interface and the correct port can be identified reliably. Explicitly selecting the host port is safer when several serial devices are present, when port names are ambiguous, or when a particular adapter must be used.
The physical port must be available to VMware Player. A host application that already has the port open can prevent the guest from communicating through it. If the port is not connected at startup, check the virtual serial device's connection state and enable Connect at power on when persistent startup access is required.
Configure output to a file
- Choose the option to send serial output to a host file.
- Browse to or enter the host output-file location and filename.
- Check that the selected directory is writable and has sufficient free space.
- Finish the wizard.
File output is useful for capturing boot messages, serial console output, application diagnostics, and other logs. Choose the path carefully: avoid an unintended existing file if overwriting would destroy useful data, and use a location that the VMware process can write to. Confirm the exact configured filename when reviewing the captured output.
Configure output to a named pipe
A named pipe is an operating-system interprocess communication endpoint. It can transfer serial data between the virtual machine and a host application, or between two virtual machines, without requiring physical serial hardware.
- Choose Output to named pipe.
- Enter or select the pipe details required by the host operating system and the intended peer endpoint.
- Configure compatible endpoint roles and matching pipe settings at both ends.
- Make sure the receiving application or peer virtual machine is prepared to open and use the pipe.
- Finish the wizard.
Named-pipe naming conventions and endpoint options depend on the host operating system. The two endpoints must agree on the pipe name and connection arrangement. For a host utility, configure the utility for the corresponding pipe endpoint. For a virtual serial link between two virtual machines, configure compatible named-pipe endpoints on both machines. A correctly named pipe will still appear nonfunctional if the peer is not running or is not ready to open it.
Complete and verify the configuration
- Click Finish to create the serial device.
- On the Hardware tab, confirm that the serial port appears in the virtual machine hardware list.
- Start the virtual machine.
- In the guest operating system, check that the new serial or COM interface is detected.
- Test communication according to the destination: send known data to the physical device, generate known serial output for a file, or exchange data with the named-pipe peer.
Windows guests commonly label serial interfaces as COM1, COM2, and similar names. Other guest operating systems may use different device names. Use the guest's device-management or hardware-detection tools to confirm which interface was assigned, then configure the guest application to use that interface.
Connection behavior
Connect at power on controls whether VMware Player automatically connects the configured virtual serial port when the virtual machine starts. It does not determine whether the serial hardware exists; the hardware can be present in the configuration while its destination is disconnected.
If the destination is unavailable, the serial port may need to be disconnected, reconfigured, or connected after the host resource becomes available. For example, a physical port may be occupied by a host application, a file path may no longer be writable, or a named-pipe peer may not yet be running.
Practical configurations
Capture boot or application diagnostics
Add a serial port, select output to a host file, and choose a writable log location. Start the guest and reproduce the diagnostic event. Review the configured file rather than assuming the output was written to the guest filesystem.
Use a legacy serial device
Map the virtual serial port to the intended physical host serial port. Select the port explicitly when the host has multiple serial interfaces, and enable Connect at power on when the guest should use the device immediately after startup.
Connect a guest program to a host utility
Configure the guest serial port to use a named pipe, then configure the host serial-aware utility for the corresponding endpoint. Start or prepare the utility so it is ready to open the pipe before testing data exchange.
Create a serial link between two virtual machines
Give each virtual machine a serial port configured with compatible named-pipe endpoints. Ensure both guests use matching pipe settings and that the peer side is running and ready to connect.
Troubleshooting
The Serial Port option cannot be added
First confirm that the virtual machine is completely powered off, not merely suspended or still running. Return to the VMware Player library, select the intended machine, and reopen Player > Manage > Virtual Machine Settings.
The guest cannot communicate through a physical port
- Verify that the selected host port is the intended one. Select it explicitly instead of using detection if necessary.
- Close host applications that may already be using the physical port.
- Check the virtual serial port's connection state.
- Enable Connect at power on if the port must be attached automatically at startup.
No output appears in the host file
- Confirm that the guest application is sending data to the assigned serial or COM port.
- Verify the configured path and filename, including whether the path is writable.
- Check available disk space.
- Make sure you are inspecting the exact file configured in VMware Player.
- Retest with known serial output.
A named-pipe connection does not establish
- Verify that both endpoints use compatible pipe names, roles, and settings.
- Confirm that the host application or peer virtual machine is running and ready to open the pipe.
- Review the host operating system's required named-pipe format and connection behavior.
The expected serial port is missing inside the guest
- Confirm that the serial device appears in VMware Player's hardware list.
- Power on or restart the guest after adding the hardware.
- Use the guest operating system's device-management tools to look for the assigned serial interface.
Summary
To add a virtual serial port, power off the correct virtual machine, open Player > Manage > Virtual Machine Settings, select the Hardware tab, and add Serial Port. Choose a physical host serial port, a host output file, or a named pipe, configure the destination, optionally enable Connect at power on, click Finish, and verify the device and data flow from inside the guest.