I think it's this.

In cybernetics and control theory, a setpoint (also set point, set-point) is the desired or target value for an essential variable of a system, often used to describe a standard configuration or norm for the system.

https://en.wikipedia.org/wiki/Setpoint_(control_system)

I'm afraid the next reference is in Catalan.

La consigna és el valor objectiu que es vol aconseguir en un sistema de control automàtic, tal com, per exemple, un controlador PID.

https://ca.wikipedia.org/wiki/Consigna

Creo que el término más usado entre la gente de instrumentación y control es "CONSIGNA"

http://forum.wordreference.com/threads/set-point.564494/

Ziegler–Nichols
This procedure was first described in a paper published in 1942—credit to Ziegler and Nichols for coming up with a tuning method that has survived almost 75 years of overwhelming technological development. The process starts with a proportional-gain-only system. You increase the P gain until the system exhibits oscillations that are sustained (i.e., stable in terms of amplitude) and regular (i.e., stable in terms of period); the oscillation does not need to be centered around the setpoint. This is the only tiresome part of the Ziegler–Nichols method. The rest is just math.

http://www.allaboutcircuits.com/projects/embedded-pid-temper...