COM ports not available

Using UNO 1.05-r2 on Dell Studio desktop with Windows 7.

Want to show Serial Monitor but get "Serial port COM3 not found". In menu, Tools, Serial Port is grayed out and shows nothing. Control Panel does not show ports, nor do I find any reference to COM ports in BIOS. What should I do next?

Install the drivers.

Are you sure it's an Uno R3? Many clones are sold as "Uno R3" clones, but actually use a different serial chip. Check the markings on the black chip nearest the USB connector - it'll either be an atmega 16u2 (use official uno drivers), or a CH340G (use the CH341SER drivers, file's called ch341ser.exe - google), FT232 (use FTDI drivers, included with at least recent versions of the IDE), or something else (google the part number).

Why are you using an ancient version of the IDE, instead of a 1.6.x version? (I recommend 1.6.5r5 - or if you're stuck with 1.0.x versions, use 1.0.6)

Thank you for your reply, DrAzzy. Yes the chip for the USB interface has “16u2” under a logo that might say “Atmega” (difficult to read, even with a magnifying glass). I downloaded IDE 1.6.7 and drivers, but Tools>Port still shows nothing, and Tools>Serial Monitor gives error “Board at COM1 is not available”.

Hmm. Does a device with a trouble icon next to it show up in device manager?

When I last posted I had installed the IDE but hadn't rebooted the computer. After doing so, the Serial Monitor works on COM3. Also, in Device Manager there is now an item for Ports, and under it is "Arduino Uno (COM3)".

Thank you very much for your help, DrAzzy.

If your UNO R2 is a Chinese version, please use this driver:

When you installed, you will see a new COM port, I presume...

Hope it works...