Serial port pinout usage

Olga Weis

In the field of telecommunications, the term ‘serial connection’ means the process of sending data via a communication channel or a computer bus serially, one bit at a time. When it’s required to connect two serial peripherals directly (without using a modem or any other Data Communications Equipment) users rely on a null modem cable.

A serial communication standard is widely used for long-distance connections or data exchange in computer networks where a parallel connection is inefficient due to synchronization issues and the cost of the cable.

As is known, serial devices exchange information via COM ports connected by a serial cable. Depending on the type of serial port, the form of a serial connector will differ.

Virtual COM Port Driver is a professional utility that allows setting custom serial port pinouts. That means, developers of complex serial communication systems will be able to manage signal lines pinout either by using already existing standard pinout presets or by creating their own COM port pinout presets.

Virtual COM Port Driver

The software offers three different options for setting signal lines pinout:


  • Standard is the default serial port pinout for serial communications with partial handshaking.
  • Loopback Mode allows virtual COM ports communicate using RS232 loopback handshaking.
  • Custom COM port pinout preset can be selected and saved by a user in the software settings.

Standard RS-232 null modem pinout preset scheme:

RS-232 null modem pinout preset RS-232 null modem pinout preset

Loopback mode pinout preset scheme:

Loopback mode pinout preset Loopback mode pinout preset

To set Custom serial connector pinout:

  1. Go to the ’Custom pinout’ tab.
  2. In the Serial Ports Explorer choose the required virtual COM port pair.
  3. Select the lines for the ‘IN’ side of the pair and connect them to the required ‘OUT’ side lines by checking the corresponding boxes.
  4. Name the preset and click the ’Save preset’ button.

There are two types of devices involved in serial communication: DTE (Data Terminal Equipment) - a controller of serial connection, computer that fits a male serial port connector, and DCE (Data Circuit-terminating Equipment) - a modem with a female COM port connector.

Data on RS-232 is normally sent using signal lines, which have the following meanings:


RTS (Request to Send) – request for data exchange indicating that the data set is ready to send information to the DTE;

CTS (Clear to Send) – a positive voltage signal indicating that a modem is able to receive data from the data terminal and that the DTE can start data transfer.

DTR (DTE Ready) – a signal sent from the DTE to a modem or other device to indicate that the serial port controller (UART) is prepared to establish a connection;

DSR (DCE Ready) – a signal sent from a modem to the data terminal to indicate that the modem is turned on, initialized, and prepared to communicate with the computer.

DCD (Data Carrier Detect) – a signal sent from the DCE to the DTE to indicate that the DCE is connected to a distant modem. Logic ’0′ means that the communication between the modems is active.

RI (Ring Indicator) – a signal sent from a modem to a computer to indicate that the DCE device (the modem) is receiving a ringing signal from the telephone line.

Virtual Serial Port Driver

Requirements: Windows (32-bit and 64-bit): XP/2003/2008/ Vista/7/8/10, Windows Server 2012, Windows Server 2016 , 5.46MB size
Version 9.0.567 () Release notes