COM-Ports get lost/mixed in Win8

Development Boards Arduino
1

Hi,

I have a problem that is bothering me. I have an application running on my Win8 Tablet that communicates with four Arduinos (2x Uno, 1x Mega, 1x own PCB with FTDI). As the Tablet has only one USB-port I have to use a hub to connect to all four boards. So far so good, but every once a while the COM-ports of the Arduinos get lost after restart of Windows and only the FTDI is available at the same COM-port.

Does somebody know if this is a problem of the ATmega16U4 (on the Uno boards) or of the hub or a Win8 specific problem?

Thanx,

Markus

2

I believe I’ve read in a couple of places that comm with the UNO (and similar) boards, without the FTDI parts, have been less than reliable.

From the SparkFun [RedBoard product page:

The RedBoard combines the simplicity of the UNO’s Optiboot bootloader (which is used in the Pro series), the stability of the FTDI (which we all missed after the Duemilanove was discontinued) and the R3 shield compatibility of the latest Arduino UNO R3.

](https://www.sparkfun.com/products/12757)

3

That is a MicroSoft/Windows issue since USB to Comm ports use dynamic allocation.

I think I have read about a way to fix the Comm port number to a device. You need to dig into Windows specific info to find a solution if it exists.

4

I use FTDI USB/serial adapters or product with an FTDI chip inside.

The windows 7 COM port number does not change as I re-plug, if I stay on the same USB hub.

I have a 7 port hub with power switch per port.