This problem is now fixed. Seems to have been related to corruption in firmware, although I dont know the cause. Try reloading your firmware first if you experience this problem. Thanks to all those who provided their own experiences and commentsby rob_paragoncb - General
@isonoob I don't see the problem with Slic3r/pronterface only with simplify3D. My hardware is a Mendel and the controller is a melzi but it has reprappro (cut-down) version of the marlin firmware installed (which is common in the UK at least) so it is quite specific. I haven't tried the full version of Marlin or any other firmware as yet. Reprappro have responded with one suggestion but I am wby rob_paragoncb - General
Good question ISONOOB!, which printer/controller/firmware are you using ? Please EVERYONE state you hardware/software configuration if posting under this topic, I wish to resolve the issue not make it more confusing. Thanksby rob_paragoncb - General
OK that's fine, but you didn't mention if you had seen the same problem or not. Also I would like to emphasize, if the USB is connected and the hardware has just been powered up then the hotend on my machine ramps up as soon as the Simplify3D software is started.... like it or not.by rob_paragoncb - General
A word of WARNING to other Reprappro Melzi users who may be using or considering Simplify3D 2.1.0. It is not my intent here to critisize anyone's hardware or software implementations but merely to inform other users of a possible risk, particularly if you happen to be fiddling around with hotends. Although the software has many useful features and generally works well with Marlin based firmwareby rob_paragoncb - General