Hi,

I am using VM pro and VS 2017 to develop several Arduino/Teensy 3.x programs, and I typically have several VS2017/VM instances running at the same time. Today I noticed that in one VS17/VM instance the serial monitor isn't reconnecting automatically when I upload a new sketch - strange.  Also, in this instance, I don't need to disconnect before uploading as I do in the others, but the connection isn't re-established automatically - I have to manually click on 'Connect'

I am used to having to disconnect before hitting F5 for recompile/re-upload, and then the serial monitor window automatically launches (if it isn't already visible) and automatically re-connects.  

If it matters, the instances where the serial monitor behavior is 'normal' (must disconnect manually to be able to re-compile/re-upload, and the monitor automatically reconnects) are connected to their respective Teensy 3.x controllers via hardwired USB cables, and the 'abnormal' one (can re-compile/re-upload without first disconnecting, but have to manually re-connect) is connected to a Mega via a Wixel pair.

Any ideas?

TIA,

Frank

Is dtr on

Dtr should always be on. Different boards use one of two methods.

If using serial USB make sure you have a loop {} at the start of setup() that waits for the port...

while (!Serial)
 {}