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hbe02 · Jan 9th, 2007, 7:08 AM

here is a question on serial communication .
in .NET framework 2.0 . you can use the serial port class to send/recieve bytes serially through the serial port of your PC .
Since im using a laptop, i do not even have a serial port.
so how can i use the USB port to communicate..? is there an alternative?

I have scanned for the serial ports available in my laptop with this method:

(Toggle Plain Text)

string[] ports = SerialPort.GetPortNames();
   
for(int i  =0 ; i < ports.Length ; i ++ )
{
    Console.Writeline(ports[i]);
}

the output is get is "COM3".

obviously i do not have COM1 or COM2 .. but what is COM3? where is it physically? can i use this instead of communicating using the USB port...?
how can i send data through the USB port anyways?

thanks

lectricpharaoh · Jan 9th, 2007, 12:10 PM

The names like COM3, LPT1, etc are derived in large part from the old DOS days. Back then, they usually (but not always) corresponded to fixed physical ports. A given machine would usually have one or two serial ports (generally COM1 and COM2), but could have more (up to four was possible without specialized hardware, but you still had to change jumpers and stuff, because COM1 and COM3 shared the same IRQ, as did COM2 and COM4).

For most modern machines, this stuff is all plug-and-play. You plug in a device, and the OS will detect it, and (attempt to) allocate the necessary resources. For most I/O devices, this involves mapping it to one or more I/O addresses, and sometimes giving it an IRQ. For USB devices, I expect that all devices on the same USB root hub share the same resources; the hardware and software multiplexes the communication through the use of control information in the data stream. That said, it's possible to get USB-to-serial and USB-to-parallel adapters. The OS and/or driver for the device will set up the adapter as a logical port that you can configure via the control panel or included software, and once this is done, you should have no trouble using the port in .NET.

[edit] It could also be that it's detecting your modem as a serial port, since it's a serial device. Check your modem in the control panel (most laptops still include one; I know mine does, and I bought it about 4 months ago) and see what port it's configured to use. [/edit]

hbe02 · Jan 10th, 2007, 7:25 PM

Very professionally said lectricpharaoh, thank you very much for clarifying this.
You were correct about my modem port being assigned to COM3. i can even change it to COM1,2.. and i have verified this using the piece of code in my first post.
I just ordered a USB to serial converter, should arrive in a few days. I will install its driver, which handles the communication and assigns it to a COM port.. after that i will be able to access it by using th eCOM port name assigned to it (being COM1,2,3,4)..
thanks..

Jan 9th, 2007, 7:08 AM	#1
hbe02 Hobbyist Programmer Join Date: Mar 2006 Location: Lebanon Posts: 148 Rep Power: 3	.NET serial USB communication here is a question on serial communication . in .NET framework 2.0 . you can use the serial port class to send/recieve bytes serially through the serial port of your PC . Since im using a laptop, i do not even have a serial port. so how can i use the USB port to communicate..? is there an alternative? I have scanned for the serial ports available in my laptop with this method: (Toggle Plain Text) string[] ports = SerialPort.GetPortNames(); for(int i =0 ; i < ports.Length ; i ++ ) { Console.Writeline(ports[i]); } string[] ports = SerialPort.GetPortNames(); for(int i =0 ; i < ports.Length ; i ++ ) { Console.Writeline(ports[i]); } the output is get is "COM3". obviously i do not have COM1 or COM2 .. but what is COM3? where is it physically? can i use this instead of communicating using the USB port...? how can i send data through the USB port anyways? thanks

Jan 9th, 2007, 12:10 PM	#2
lectricpharaoh Caffeinated Neural Net Join Date: Jun 2005 Location: Wet west coast of Canada Posts: 1,126 Rep Power: 5	The names like COM3, LPT1, etc are derived in large part from the old DOS days. Back then, they usually (but not always) corresponded to fixed physical ports. A given machine would usually have one or two serial ports (generally COM1 and COM2), but could have more (up to four was possible without specialized hardware, but you still had to change jumpers and stuff, because COM1 and COM3 shared the same IRQ, as did COM2 and COM4). For most modern machines, this stuff is all plug-and-play. You plug in a device, and the OS will detect it, and (attempt to) allocate the necessary resources. For most I/O devices, this involves mapping it to one or more I/O addresses, and sometimes giving it an IRQ. For USB devices, I expect that all devices on the same USB root hub share the same resources; the hardware and software multiplexes the communication through the use of control information in the data stream. That said, it's possible to get USB-to-serial and USB-to-parallel adapters. The OS and/or driver for the device will set up the adapter as a logical port that you can configure via the control panel or included software, and once this is done, you should have no trouble using the port in .NET. [edit] It could also be that it's detecting your modem as a serial port, since it's a serial device. Check your modem in the control panel (most laptops still include one; I know mine does, and I bought it about 4 months ago) and see what port it's configured to use. [/edit] __________________ And once again, Probability proves itself willing to sneak into a back alley and service Drama as would a copper-piece harlot. - Vaarsuvius, Order of the Stick

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Jan 10th, 2007, 7:25 PM	#3
hbe02 Hobbyist Programmer Join Date: Mar 2006 Location: Lebanon Posts: 148 Rep Power: 3	Very professionally said lectricpharaoh, thank you very much for clarifying this. You were correct about my modem port being assigned to COM3. i can even change it to COM1,2.. and i have verified this using the piece of code in my first post. I just ordered a USB to serial converter, should arrive in a few days. I will install its driver, which handles the communication and assigns it to a COM port.. after that i will be able to access it by using th eCOM port name assigned to it (being COM1,2,3,4).. thanks..

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Programming Forums > Application Development > Other Programming Languages

.NET serial USB communication