Isaac Asimov's Three Laws of Robotics.
1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2. A robot must obey orders given it by human beings except where such orders would conflict with the First Law.
3. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
Later, Asimov added the Zeroth Law: "A robot may not harm humanity, or, by inaction, allow humanity to come to harm"; the rest of the laws are modified sequentially to acknowledge this.
In practice, the second and third law are reversed. We build firmware and hardware interlocks into devices, computer peripherals and industrial robots so that an errant programmer cannot send a command that will damage the machine.
A simple example is a car's automatic transmission. You cannot put it into reverse when going forward at a certain speed.