Thanks for the clarification. On Windows 10, I also had problems.

Managed on one occasion to get firmata isConnected to return True, but writing to a port had no effect. I got multiple error messages; I think one of them referenced a SerialPiort primitive, consistent with your findings. 

Playing with VMs is beyond me, so I will give PyFirmata a try.

With much appreciation,

Lou Cleveland

On Nov 30, 2018, at 2:42 AM, Nicolai Hess <nicolaihess@gmail.com> wrote:

Good to know!

Am Fr., 30. Nov. 2018 um 02:25 Uhr schrieb Ricardo Moran <richi.moran@gmail.com>:
Hi,

I think I found a bug with the named serial ports in windows.
I can open a named port without problem the first time but if I close it and try to open it again it fails until I restart the image. This doesn't happen with numeric ports. I could reproduce this bug in both Squeak5.2 and Pharo6.1 (both using windows 8.1). 

I think the problem is that SerialPort>>#primClosePortByName: calls the "primitiveSerialPortCloseByName" but I couldn't find this primitive anywhere in the SerialPlugin source (https://github.com/OpenSmalltalk/opensmalltalk-vm/blob/Cog/src/plugins/SerialPlugin/SerialPlugin.c). So I'm guessing that the port is never properly closed. 

I added the missing primitive (find attached) and recompiled the vm, and now it seems to work. So my question is: how can I contribute this small fix? Should I commit to the VM Maker Inbox repository? 

Thanks,
Richo