PySerial could not open port COM4: [Error 5] Access is denied - please help

[Grant Edwards]

On 2012-06-27, Adam <adam at no_thanks.com> wrote:

> The Python script needed a call to ser.close() before ser.open() in
> order to work.

IOW, the port opened OK, but when you tried to open it a second time
without closing it first, _that's_ when the .open() call failed.

That's a restriction built in to Win32.  You can't open a serial port
that's already open.  [Linux doesn't have that restriction.]

Why do you need to open it a second time?

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