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How to share COM port between applications?

Olga Weis Olga Weis Dec 10, 2019

Table of contents:

  1. Serial Port Splitter: What it is and how it works?
  2. How to share COM ports between applications [step-by-step guide]
  3. VSPD PRO benefits beyond simply splitting serial port
  4. Hardware Alternatives to Serial Port Splitter software
  5. Scenarios for successful application of the serial RS232 port splitter

Serial Port Splitter: What it is and how it works

Splitting a serial port means to share the interface with more than one application simultaneously. All attached applications get the same data flow from the serial port. There are both hardware and software solutions that can be employed to allow you to share a COM port.

Serial Port Splitter

Serial Port Splitter, also known as Virtual Serial Port Driver PRO (VSPD PRO) is a software tool developed by Electronic Team that is designed to enable the user to create an unlimited number of virtual COM ports that emulate and behave as if they were actual physical ports. The ability to create these virtual serial ports in any number allows you to share real COM ports between applications. This excellent application also offers a simple method to split serial port data without the need for additional hardware.

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All virtual serial interfaces created with the help of Virtual Serial Port Driver behave exactly like real ones, so you will have no problem finding and accessing them in the Device Manager of your machine.
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Serial data splitter software works by taking a single serial port, say COM1, and sharing it into several virtual ports (COM2, COM3, COM4, etc.). Each of these newly created virtual ports will appear in your device manager as if they were actual hardware interfaces and will emulate all of the settings of a physical port. Now, applications can be assigned to the virtual serial ports through a unique identifier, eliminating compatibility issues. You can now assign COM2, COM3, etc. where previously only one application could be assigned to COM1 at a time.

How to share COM ports between applications?

Here are step-by-step instructions on how to share COM port data between several applications using Serial Port Splitter.

  1. Launch VSPD Pro on your Windows machine.

  2. Open the "Share" tab and select the serial port that you intend to share.

  3. Choose the applications that will be sharing access to the port and set their custom rights. You will need to specify the full path to each application and then click the “Set custom rights” button to proceed. Set custom rights
  4. Toggle the “Read”, “Write”, and “Control” option for each application.
    Note: Only one app can control the device, so in most cases “Read/Write” is a sufficient level of access when sharing a device or port.

  5. Click on the “Add share” button to create a bundle that will appear in the bundle tree. The connected applications will now share the port you selected at the beginning of this procedure.

VSPD PRO benefits beyond simply splitting serial port

Besides being an excellent software serial port splitter, Virtual Serial Port Driver Pro is packed with other features and capabilities that increase your productivity when working with serial protocols and interfaces. In addition to splitting serial ports, here are some of the other tasks that can be accomplished with this software application:

  • Joining COM Ports - VSPD Pro lets you link multiple physical COM ports to one virtual port. A serial application connected to this virtual serial port will receive data simultaneously from all the joined real COM ports. This allows you to redirect data from multiple devices back to one application.

This can be useful for a monitoring application that may need to access many serial devices in an industrial automation setting. With a single physical connection, you can monitor as many virtual connections as your system can handle.

  • Automated Port Switching - If you have an application that can only work with a limited number of ports the Switcher feature of VSPD Pro is just what you need. It allows you to combine several physical ports into one virtual one and create a switcher to the newly created virtual port in your application.

When your program needs a serial interface the switcher detects an open COM port from the list of joined ports and makes it available to the app. Your program always gains access to a port as if it was the same physical port.

  • Creating Bundle Connections - Complex bundles of serial interfaces can be created and managed with this advanced feature of VSPD Pro.

It gives you the ability to transmit serial data in and out of an unlimited number of physical or virtual serial interfaces. Data received at the ‘IN’ side of the bundle will be sent to every serial interface on the ‘OUT’ side of the bundle. This transmission mode works in both directions. You can manage the hardware control lines by setting a main port for each side of the bundle. This facility can be very helpful when multiple devices or applications need to communicate with the same serial device.

  • Merging COM Ports - Using this feature you can add any number of physical or virtual serial ports to a single serial port bundle not divided into ‘IN’ and ‘OUT’ sides. All data sent to one port is replicated to all other ports in the bundle. All devices and applications can now change data with multiple devices and applications at the same time.

Hardware Alternatives to Serial Port Splitter software

Using a great software application like Serial Port Splitter is not the only way to share a COM port. Serial port splitter hardware is available in a number of varieties that can also allow you to share serial ports, though not with the same flexibility as that offered by the software solution. They are marketed under a number of names. Two of the most popular options are:

DB9 Splitter Box

A DB9 splitter box is a device that has a single male or female DB9 connector at one end and splits the signal into multiple DB9 connectors of the opposite type at the other end. You might have a single male connector on one end and two female connectors at the other end. This type of device allows two computers or applications to be attached to a single serial device.

A DB9 splitter box

Serial Cable Splitter

A serial cable splitter is just another term for a DB9 splitter box. They all work in a similar fashion, offering multiple out connections from a single input.

Serial Cable Splitter

There are some advantages and disadvantages to using a hardware solution when you need to split serial ports. Let’s look at the pros and cons of hardware serial splitters.


  • No software installation is required.
  • They can be used sequentially with multiple machines.


  • Physical limitations exist regarding cable length.
  • Limited by the number of physical connections built into the device.
  • They introduce additional cables that need to be managed.

Summing up, the software solution for splitting and sharing serial ports offers much more flexibility than a hardware solution. Additional features such as bundling and COM port merging are not possible by simply using another hardware component. Using a tool like Serial Port Splitter gives you the same capabilities of a hardware solution, plus a host of additional features that the hardware cannot provide.

Scenarios for successful application of the serial RS232 port splitter

There are many times when being able to split and share COM devices can be the best way to solve a usage problem. Let’s take a look at some situations where having the ability to split RS232 or other serial interfaces can be useful.

Ham radio enthusiasts scenario.

Ham radio operators need to be able to control and access their transceivers. The transceiver is usually attached to a computer via a standard RS-232 interface. Most ham radio operators will want to have several applications running at once and they all need to communicate with the transceiver through a single COM port. That cannot be done on the Windows operating system as Windows limits the number of connections to a COM device to a single one.

Share RS232 transceiver between apps

If you are trying to run a station log book as well as station control software you are forced to shut down one application before opening the other one. This is not an efficient way of operating although it is a common method that ham operators must resort to in order to pursue their hobby. A better alternative would be to install and use Serial Port Splitter to share RS-232 signals from a single COM device to multiple virtual interfaces. This enables each software application needed to operate the radio to have their own, simultaneous connection to the transceiver.

Split COM device to multiple virtual interfaces

Sailing navigation

Computer controlled navigation is possible using an application that connects to a GPS device. The GPS is often attached to the computer by way of a serial connection. Accurate planning of the route can be done with a single connection to the GPS, but what if you want to log your route as well? You are faced with the prospect of purchasing another GPS unit to attach to your logging application.

Here again, employing a serial splitter software application can save you the expense of purchasing another device as well as keep your working area uncluttered. Install the software and you can share your GPS unit with as many applications as you wish.

Sailing navigation solution

As you can see, having the ability to split a serial port can be very useful in a number of situations. Using serial splitter software enables you to save money and increase your productivity without the addition of a single piece of hardware.

Collecting weather station data

Many hobbyists maintain personal weather stations on their property that they rely on for immediate and accurate temperature, humidity, and wind measurements. In some cases, they will post this data to a personal website and may also want to submit that data to public weather sites.

Unfortunately, the chances are low that the data can be shared directly between the personal weather program and the public site. More likely is that the data formats will be different, necessitating two connections to the raw data generated by the weather station. Splitting the serial port that is connected to the weather station is the easiest way to get the data to both programs so they can manipulate it as needed. A virtual COM port splitter is a perfect software solution for this scenario.

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