Creating Virtual Port Pairs

The feature to create pairs of virtual serial ports is available in both the Standard and the PRO editions of Virtual Serial Port Driver.

You can create a new port pair using one of the four methods you like the most.

Method 1. From the Main screen:

Click the “Pair” button:

Pair button

Method 2. From the “New bundle” menu:

Click “New bundle” in the upper-left corner and pick the “Pair” option on the drop-down menu.

New bundle

Method 3. Using the “Add a new pair” button:

  1. Go to the “Pair” tab by clicking the respective icon on the vertical menu at the left. 
  2. Click the “Add a new pair” button.

Add a new pair

Method 4. From the “Pair” tab:

  1. Go to the “Pair” tab by clicking the respective icon on the vertical menu at the left. 
  2. Click the “+” icon.

From the Pair tab
     3. Choose names for your new ports from a dropdown list:

Choose names

Note: If a port name is already in use in some other bundle, it won’t be shown in the list.

You can create ports with custom names too (letters plus symbols – and _):

custom names
Enter the new bundle’s description for easier identification (optional). Also, you can tick the respective checkboxes if you need to enable strict baudrate emulation and/or want to create this bundle for your current session only. Choose the pinout preset for the new bundle or set a custom one:

Choose the pinout preset
4. Click the “Create” button. Now you can click this port bundle in the Bundle tree to view its settings:

Create button


Break and restore the connection in a port pair

Emulating physical line break

On the “All” tab, select a pair of ports you want to emulate a line break for, then click the “Break” button:

Break button
After that, all incoming signal lines (DCD, DSR, CTS, RI) will be dropped, and data from one port won’t be transferred to another one.

Restoring the connection

On the “All” tab, select the pair of ports you’ve emulated a line break for, and click the “Restore connection” button:

Restore connection button


Set Custom Pinout 

At the “Custom pinout” tab section, you can choose from signal lines pinout presets or create your own pinout preset just in a couple of clicks.

Set Custom Pinout

Pinout presets:

Standard: the default signal lines pinout RS232 null modem scheme with partial handshaking:

default signal lines pinout RS232
null modem scheme
Loopback: the RS232 null-modem scheme with loopback handshaking:

loopback handshaking

loopback handshaking

Setting the custom pinout:

  1. On the “All” tab, select the virtual serial pair you want to set the custom pinout for. 
  2. Use the radio buttons to select the RTS or DTR signal line on the IN side, then use the checkboxes at the OUT side to set the pinout to your liking.
  3. To save settings, click the “Create” button. The name to the new custom pinout will be assigned automatically (e.g. DTR->CTS,DCD,RTS->DSR), and it will be available as a preset option for other virtual port pairs.
Note: Other null-modem schemes are available here.

Signal lines description:

  • RTS (Request to Send) – This signal is asserted (logic ‘0’, positive voltage) to prepare the DCE device for accepting transmitted data from the DTE device. Such preparation might include enabling the receive circuits9 or setting up the channel direction in half-duplex applications. When the DCE is ready, it acknowledges by asserting Clear to Send.
  • DTR (DTE Ready) – This signal is asserted (logic ‘0’, positive voltage) by the DTE device when it wishes to open a communications channel. If the DCE device is a modem, the assertion of DTE Ready prepares the modem to be connected to the telephone circuit, and, once connected, maintains the connection. When DTE Ready is de-asserted (logic ‘1’, negative voltage), the modem is switched to “on-hook” to terminate the connection.
  • CTS (Clear to Send) – This signal is asserted (logic ‘0’, positive voltage) by the DCE device to inform the DTE device that transmission may begin. RTS and CTS are commonly used as handshaking signals to moderate the flow of data into the DCE device.
  • DSR (DCE Ready) – When originating from a modem, this signal is asserted (logic ‘0’, positive voltage) when the following three conditions are all satisfied:
    • The modem is connected to an active telephone line that is “off-hook”
    • The modem is in data mode, not voice or dialing mode
    • The modem has completed dialing or call setup functions and is generating an answer tone
  • DCD (Carrier Detect) – This signal is relevant when the DCE device is a modem. It is asserted (logic ‘0’, positive voltage) by the modem when the telephone line is “off-hook”, a connection has been established, and an answer tone is being received from the remote modem. The signal is de-asserted when no answer tone is being received, or when the answer tone is of inadequate quality to meet the local modem’s requirements (perhaps due to a noisy channel).

RI (Ring Indicator) – This signal is relevant when the DCE device is a modem and is asserted (logic ‘0’, positive voltage) when a ringing signal is being received from the telephone line. The assertion time of this signal will approximately equal the duration of the ring signal, and it will be de-asserted between rings or when no ringing is present.