Operating modes of the POS / POS_1 function blocks

The following operating modes are defined according to the 'enMode' variable:

POS_REL	Relative positioning
POS_REL_RETRIG	Relative positioning, retriggerable
POS_REL_RETRIG_EXT	Relative positioning, retriggerable, enhanced function ('POS_1' only)
POS_MODULO	Modulo positioning
POS_INTERPOSED	Positioning with override function with retraction
POS_INTERPOSED_NB	Positioning with override function without retraction

 

All input variables, with the exception of the position, can be changed during the positioning process.

• 'diPosition'
  The position value is saved at the start of positioning (positive edge at 'boStart'). If the position is required again during the positioning process, e.g. in 'POS_REL_RETRIG' or 'POS_MODULO' mode, it is always the saved position value that is referenced.
  However, a new position value can be transferred in 'POS_REL_RETRIG_EXT' mode in the context of retriggering.
• 'diOffset'
  In positioning with override function ('POS_INTERPOSED' or 'POS_INTERPOSED_NB'), the 'diOffset' is added to the saved 'diPosition' when there is a positive edge at 'boStop'.
• Changes in value during the deceleration phase (POS (FB), POS_1 (FB) Figure: Principle of positioning, t3 ≤ t ≤ t4) are ignored.
• In some modes (e.g. 'POS_INTERPOSED_NB'), the deceleration 'udDecel' is automatically increased to the smallest possible valid value if the deceleration setpoint is not compatible with predefined positioning behavior. In this case the corresponding warning is output (iErrID = 7: deceleration value corrected).