How to Show Available Serial Ports in Visual Basic. This topic describes how to use My. Computer. Ports to show the available serial ports of the computer in Visual Basic. To allow a user to select which port to use, the names of the serial ports are placed in a List. Now that we have created our serial port object and opened the port, we now want to read from the serial port. Here are the basic read functions there are several. Visual Basic Serial COM Port TutorialPart 1 download the source code httpssourceforge. How can i add more than 1 LED. I Added more slots in visual basic but how can i add more in the arduino sketch These examples are suitable for use in Visual Basic, Word, Excel and Access. The serial port ActiveX object can be inserted by VBA code see the first example or be. Box control. Example This example loops over all the strings that the My. Computer. Ports. Serial. Port. Names property returns. These strings are the names of the available serial ports on the computer. Typically, a user selects which serial port the application should use from the list of available ports. Serial Port And Visual Basic' title='Serial Port And Visual Basic' />In this example, the serial port names are stored in a List. Box control. For more information, see List. Box Control. Sub Get. This topic describes how to use My. Computer. Ports to dial a modem in Visual Basic. Typically, the modem is connected to one of the serial ports on the computer. For. Windows Serial Communications component library. Developer tools for serial port communications Supports RS232, multidrop RS422 and RS485 ports, virtual serial ports. Visual Basic Serial COM Port TutorialPart 2 download the source code httpssourceforge. Serial-Terminal-in-visual-basic.jpg' alt='Serial Port And Visual Basic' title='Serial Port And Visual Basic' />Serial. Port. Names. Show all available COM ports. For Each sp As String In My. Computer. Ports. Serial. Port. Names. List. Box. 1. Items. Addsp. This code example is also available as an Intelli. Sense code snippet. In the code snippet picker, it is located in Connectivity and Networking. Serial Port And Visual Basic' title='Serial Port And Visual Basic' />For more information, see Code Snippets. Compiling the Code This example requires Robust Programming You do not have to use the List. Box control to display the available serial port names. Instead, you can use a Combo. Box or other control. If the application does not need a response from the user, you can use a Text. Box control to display the information. Note The port names returned by My. Computer. Ports. Serial. Port. Names may be incorrect when run on Windows 9. To prevent application errors, use exception handling, such as the Try. Catch. Finally statement or the Using statement, when using the port names to open ports. See Also. Ports. How to Dial Modems Attached to Serial Ports. How to Send Strings to Serial Ports. How to Receive Strings From Serial Ports. Programming The Parallel Port In Visual Basic. If you have built any of the interfaces on my circuits page and now want to know how to actually make use of them, this page is for you. This is a simple introduction to programming the parallel port in Visual Basic. Note that most of the concepts in this page apply to both 1. VB. If you are interested in using QBasic to control the port, see Programming The Parallel Port In QBasic. What this document will not do is give you lots of details on using bi directional ports, DMA and other advanced topics. This document assumes that you are familiar with the basic functions of Visual Basic itself. Now before we go any further, we must figure out a way around some limitations built into Visual Basic. VB cannot directly access the hardware on a system. All hardware requests must go through Windows. Because of this, the closest we can get to manipulating the parallel port is with the Printer object. While this is all fine and good when you want to actually print something, it is useless when we want direct hardware control. There may be API calls to get round this, but as of yet I have been unable to find any. In order to control the port directly, we must use something external to our program. It just so happens that there is a great, free product that does exactly what we want. It is a DLL from a company called Soft. Circuits. You can download this DLL from their Programming Tools and Libraries page. Use VBASM. DLL in the VBASM. ZIP package for VB1, VB2, VB3 or VB4 1. Bit. Use WIN9. 5IO. DLL in the WIN9. IO. ZIP package for VB4 3. VB5 or VB6. No matter which one you choose, the DLL file itself must be in the windowssystem directory in any machine the interface control software is to be used or developed on. Please note that no matter which DLL you use, this wont work under any Windows NT based system, including Win. NT, Win. 2K, XP, Vista, Win. Windows Server. NT based systems do not allow direct hardware access to non drivers. Now that we have that finished with, lets get to the port. The parallel port is made up of three different sections. These are the data lines, control lines and status lines. There are 8 data lines, and they are the primary means of getting information out of the port. In simple projects, you will be concentrating mostly on the data lines. The control lines are another 4 outputs. They are meant to provide control signals to the printer such as form feed or initialize. Gkrellm Mac here. The status lines are a standard parallel ports only inputs. There are 5 of them. They were meant to allow the printer to communicate things such as error, paper out and busy to the PC. Each section is accessed by its own address and will act independently from the rest. This is almost as if they were different ports. The addresses are as follows. Port. Address DecimalAddress HexData Lines. Control Lines. 89. Ah. Status Lines. You need to know the address of the port you want to use. You will also need two other things the command to access the port and the number you want to set it to. The command will be explained in a little while. The ports work with numbers. These can be expressed in hex, binary or decimal, but for this document all values will be expressed in decimal. Its just easier that way. Anyway, you operate the port by sending it a number that represents the binary pattern of the physical outputs on the port. For example, to set the 8 data lines to 1. To set them to 0. Note that these are all 8 bit binary numbers, and the port is also 8 outputs. Coincidence I think not. Before we can use any of the functions contained within either DLL, we must declare them. These declarations are to be placed in any module in your program in the GeneralDeclarations section. For 1. 6bit VB VBASM. DLL, use. Declare Function vb. Inp Lib VBASM. DLL By. Val n. Port As Integer As Integer. Declare Sub vb. Out Lib VBASM. DLL By. Val n. Port As Integer, By. Val n. Data As Integer. For 3. 2bit VB WIN9. IO. DLL, use. Declare Sub vb. Out Lib WIN9. 5IO. DLL By. Val n. Port As Integer, By. Val n. Data As Integer. Declare Sub vb. Outw Lib WIN9. IO. DLL By. Val n. Port As Integer, By. Val n. Data As Integer. Declare Function vb. Inp Lib WIN9. 5IO. DLL By. Val n. Port As Integer As Integer. Declare Function vb. Inpw Lib WIN9. 5IO. DLL By. Val n. Port As Integer As Integer. Once you declare the functions, you will have two new commands available. These are vb. Inp and vb. Out. vb. Out is a statement and is used to send a bit to a port, like the following. Out port,number. We will get to vb. Inp later. As you can see, the two parameters required are the port address and the value we want to set it to. The address can be decimal or hex, as can the value. Because there are only 8 data lines, we can only send a maximum of 2. The examples below illustrate sending a few different bit patterns to the data lines. Of course, you can also turn on more than one bit. Note that when you send a bit pattern to the port everything that was there previously is cleared. This is a convenience and also a annoyance. For example, what if we want bit 2 to always stay at 1, but want to turn bit 5 on and off in sequence Every time we set bit 5, bit 2 is turned off, and vice versa. We will discuss how to get around this when we get to the vb. Inp function. The control lines are just as easy to control, but there are a few differences. First, the address of the port is 8. Second is that there are only 4 outputs, so the highest decimal representation of the binary bit pattern you will be using is 1. Outputting information is easy, and inputting is just as easy. If you actually want to get information into the computer, you will be using the 5 status lines. Reading the bit pattern of a port is done using the vb. Inp function. This function is used in the following way. Inpport. So if we wanted to get the current status of the status lines port 8. Port. Numvb. Inp8. Port. Num would then contain the decimal representation of the binary bit pattern present at the 5 status lines. If you try this and get 3. When there is nothing connected to the input of a TTL logic chip, a high input is usually assumed. Not only can you perform inputs on ports actually designed for inputting, but you can also use vb. Inp to read the status of an output port. For example. Port. Numvb. Inp8. 88. The above would set Port. Num to the current value of the data lines port 8. We can prove this by doing the following. Port. Numvb. Inp8. Msg. Box Port. Num. If all is well, the number 5. Now that we know the vb. Inp function we can use it to solve the problem of keeping the state of one bit while changing the state of another. For that we will define a subroutine that uses both functions. SUB Out. PortPort. Address, Out. Num. Port. State vb. InpPort. Address. Port. Num Port. State Out. Num. Out Port. The Sims 2 Wings S. Address, Port. Num. Note how the sub adds the current port state to the number we send it. This has the effect of keeping all previous bits at the same state they were in, but either turning on or off the bit or bits represented by the number we pass to the sub. This also requires a change in the way the function is used. To turn on bit 1, we would. This example assumes a current port status of 0 0. If bit 1 is already high, you will get unexpected results, so keeping track of the port is important. To turn bit 1 back off, we would. Out. Port 8. 88, 1. Now this sub introduces a problem. How do we clear everything on the port as if we were doing vb.