Derivator

Name

Description

MLDerInit

Initializes an derivator object.

MLDerReadInModPos

Returns the Input ModuloPosition of the derivator block.

MLDerWriteInModPos

Sets the Input ModuloPosition of the Derivator block.

Purpose

The derivator is a general pipe block whose purpose is to calculate the first derivative of its input values with respect to time.

  • It is used to change incoming position into velocity.
  • It works together with the GEAR block as gearing in velocity to avoid jumps when suddenly changing the position.

Derivator - 'No Modulo' Mode

Figure 1: Derivator - No Modulo Mode

Derivator - Modulo Mode

Figure 2: Derivator - Modulo Mode

Initial Behavior

The first calculation of a derivator pipe block just after the pipe installation indicates zero regardless of the initial input value.

Parameters

Parameter

Description

InputModuloPosition

Value of the period of a cyclic system expressed in User units.

  • The parameter INPUT_MODULO_POSITION is defined to correctly manage the periodicity (modulo) of the input values.
  • 0 (zero) indicates the input signal does not use the modulo operation.

Example: If the input value increases each millisecond by one (degree), then the output value is a thousand (degrees per second).

  • If the input value skips suddenly from 359 to 0:
    • If VALUE PERIOD = 360, the output continues to indicate 1000 (degrees per second).
      • This indicates that the roll-over into the next period has been properly handled.
    • If VALUE PERIOD = 1000, the output indicates -359,000 (degrees per second).
      • This indicates that the input has incorrectly interpreted roll-over as a 359 degree change in input in one millisecond.

Associated Data

  • OutputValue: Output value of the data flows.
  • IsReady: Boolean set to TRUE when the pipe block is ready.