Apparatus and methods for controlling and communicating with downwhole devices

Abstract

Apparatus and methods for controlling and communicating with one or more tools in a downhole tool string including a tractor, an auxiliary tractor tool, a logging tool, a safety sub, a release mechanism, a unit containing sensors for monitoring downhole conditions, a setting tool, and a perforating gun. Also provided are apparatus and methods for controlling and communicating with one or more perforating guns, release devices, and explosive devices in a string to be lowered into a wellbore. Control and communication are accomplished by sending signals from the surface to control switches in the control units on the tool, with redundant switches for safety, to state machines in the respective control units, each state machine returning a signal verifying switch status to the surface. Control and power functions are accomplished with voltage of different polarities for safety.

Dependencies are inferred from the claim text.