Setpoint signal

An example setpoint signal (target value) and measured response signal (realized output value) of a control system.

Setpoint (a.k.a reference) signal is a signal that will be used as target value in control systems. Typical occurrencies of setpoint signals in GD products are:

• Position setpoint
• Velocity setpoint
• Torque setpoint

I.e. position setpoint value may be "1234" which could mean a target position of 1234 mm in some linear actuator. Or torque setpoint of 5.0 could mean that motor is asked to produce 5 Nm torque.

Physical setpoint signal types

Setpont signals may have several representations in real world such as:

• Analog setpoint signal
• Pulse and direction signals
• PWM signal
• Serial communication command

In these cases there will be a conversion between input and output units. For example when using +/-10V as velocity setpoint, the relation between input to output types could be 1 Volt per 100 rpm (or any other scale).

Setpoint signal characteristics

	Analog	Pulse & dir or Quadrature	PWM	Serial / Network
Scale & range	Absolute (limited)	Incremental (infinite)	Absolute (limited)	Absolute (near infinite) Incremental (infinite)
Setpoint uses in motion control	Torque, velocity	Position, velocity	Torque, velocity	Position, torque, velocity, parameters
Pros	Widely used Easy to measure	Widely used Exact Noise robust	EMI noise robust Precise	High resolution & accuracy Reduce wiring More functions than just setpoint
Cons	EMI noise sensitive Offset & gain errors	Limited resolution at low frequency Need reference zeroing because incremental	Various "standards", sometimes incompatible	Many standards Usually incompatible with other standards

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