ELM 327 USB to 8" Android (Marshmallow) on dash using Torque HP application.
Micro USB (OTG - On the go cable) to USB ELM 327
Unfortunately OTG will not allow data and charging at the same time.... working on this.
Tablet is in sleep mode with engine off and then turns on automatically with key on.
Most of the time, I am not charging the smartdevice while it is in use, as that tends to really increase the internal temps, very warm to even hot if you touch it. And I have the OTG cables, so all I need to do is get a hardwired ELM device and check it out.