Using Serial on Python / Win7

Question

I am trying to interface with a serial WWAN modem (for diagnostics /signal strength measurement purposes). This is via the onboard COM1 (115200-8-n-1) on my desktop, the con

Answer 1

You don't need to call open. The constructor already does that, and on Windows whoever opens a COM port has exclusive access to it until they close it.

As to the second problem, take a look at How can I fix "[Error 6] The handle is invalid." with PySerial