VSPD Pro troubleshooting

How can I set main port in a bundle?

Main port in a bundle is a port which can manage control lines (RTS/CTS, DSR/DTR, DCD, RING) on the other side of the bundle.

When you split a real serial port, this port is always main at the IN side of the bundle.
When you join several real ports, the virtual port is always main at the OUT side of the bundle.

When you redirect serial traffic from a real port to another port, ports of both sides are main ones.

When you share a real port between several applications, ports of both sides are main ones. The application with “Control” access rights will manage port parameters provided it was the first to open the port. If not any of the applications in a bundle has ‘Control’ access rights, none of them will be able to manage the parameters of the shared port.

When you create a complex port bundle, the main port is always set manually. If it is not done, there will be no main port in a complex bundle. A virtual port which is set as main in a complex bundle manages dynamic parameters of a real port on the other side of the bundle. If a shared port is set as main in a complex bundle, any application with “Control” access rights will be able to manage real port’s parameters.

Note 1: For more information on the dynamic port parameters, see the section “How can I set custom real port settings?” provided below.

Note 2: Main port is marked with a small exclamation mark icon. Learn more about different port icons here.

How can I set custom real port settings?

Port Settings parameters can be empty, which means that dynamic connection parameters will be used instead. In that case, real port parameters will depend on the parameters of the main port of the opposite side. To transfer all parameters, the opposite main port should be of Virtual or Shared type. If a port is of Real type, it will open with the last applied parameters.

However, you can adjust port settings manually. To do this, choose the “Use custom settings” option (Toolbar > Port settings) and set different values such as:


Possible baud rate values are: 110, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 38400, 56000, 57600, 115200, 128000 and 256000 bauds. 9600 is selected by default.
You may also put any custom baudrate value that you need, for example, 150000. Place mouse cursor anywhere inside this field and hit the “Backspace” button.

Alternatively, you may set custom baud rate value via the registry (for OEM license owners). For example:

“COM1 [Communications Port]”=”Real|15000,O,6,2,X”

Custom port settings are set like this: baud rate– 15000, parity – odd, data bits – 6, 2 stop bits, flow control – Xon/Xoff.

To get more information about working with Windows registry, you should get OEM license.


The parity bit in each character can be set to “No parity”, “Odd”, “Even”, “Mark”, and “Space”. The default value is “No parity”.

Data Bits

Possible values are: 5, 6, 7 and 8. “7” is selected by default.

Stop Bits

Possible values are: “1 stop bit” and “2 stop bits”. Default value is “1 stop bit”.

Flow control

Possible values are: “None”, “Hardware”, “Xon/Xoff”. The default value is “None”.

Note: If you have faced any issues while transmitting data via ports used by VSPD Pro, with Flow Control set to Xon/Xoff, please, contact us at support@eltima.com and describe the issue in detail.

Get more info on modifying real port settings here.