Visual Basic 6.0 Serial Port Programming

Visual Basic 6.0 Serial Port Programming: A Beginner's Guide

Serial port programming is a useful skill for communicating with external devices such as sensors, microcontrollers, modems, and printers. In this article, you will learn how to use Visual Basic 6.0 to send and receive data from the serial port of your computer.

What is a Serial Port

A serial port is a physical interface that allows data to be transferred between a computer and another device in a serial or sequential manner. Serial ports are also known as RS-232 ports, COM ports, or UART ports. Serial ports have several pins that can be used for different purposes, such as transmitting and receiving data, controlling the flow of data, and signaling the status of the connection.

How to Access the Serial Port in Visual Basic 6.0

To access the serial port in Visual Basic 6.0, you need to use the MSComm control, which is part of the Microsoft Comm Control 6.0 component. You can add this control to your project by selecting Project > Components > Microsoft Comm Control 6.0 from the menu bar. Then, you can drag and drop the MSComm control onto your form.

The MSComm control has several properties and methods that allow you to configure and manipulate the serial port. Some of the most important ones are:

CommPort: This property sets or returns the number of the serial port to use. For example, MSComm1.CommPort = 1 means using COM1.

Settings: This property sets or returns the parameters of the serial port, such as baud rate, parity, data bits, and stop bits. For example, MSComm1.Settings = \\\"9600,N,8,1\\\" means using 9600 baud rate, no parity, 8 data bits, and 1 stop bit.

PortOpen: This property sets or returns whether the serial port is open or closed. For example, MSComm1.PortOpen = True means opening the serial port.

InputMode: This property sets or returns how the data received from the serial port is interpreted. For example, MSComm1.InputMode = comInputModeText means using text mode.

InBufferCount: This property returns the number of bytes available in the input buffer of the serial port.

Input: This property returns the data received from the serial port as a string.

Output: This property sets or returns the data to be sent to the serial port as a string.

InStr: This method searches for a specific string in the input buffer of the serial port and returns its position.

InStrRev: This method searches for a specific string in the input buffer of the serial port from right to left and returns its position.

RThreshold: This property sets or returns the number of bytes that trigger the OnComm event when received from the serial port.

SThreshold: This property sets or returns the number of bytes that trigger the OnComm event when sent to the serial port.

OnComm: This event occurs when data is sent or received from the serial port or when an error occurs.

CommEvent: This property returns a value that indicates what caused the OnComm event.

ErrorMsg: This method displays a message box with an error description when an error occurs.

DTRenable: This property sets or returns whether to enable or disable Data Terminal Ready (DTR) signal on pin 4 of the serial port.

DTRHolding: This property returns whether Data Set Ready ( aa16f39245