Typical System Structure; Method Of Operation - WEST POS-124-U-PFN Technical Documentation Manual

3.2 Typical system structure

This minimal system consists of the following components:
(*1) Proportional valve with OBE
(*2) Hydraulic cylinder
(*3) Position sensor
(*4) interface to PLC with analogue and digital signals
(*5) POS-124-U control module

3.3 Method of operation

This control module supports simple point-to-point positioning with hydraulic drives. The system works based
on the principle of stroke-dependent deceleration, i.e. the control gain (deceleration stroke) is set via param-
eters D:A and D:B. Alternatively it can be used in NC mode by setting the loop gain parameters and maxi-
mum speed. In this mode the drive will move with controlled velocity to the target position. The movement
profile will be calculated by giving acceleration and speed demand.
The deceleration characteristics can be set linearly (LIN) or approximately quadratically (SQRT1) via the
CTRL parameter. For normal proportional valves SQRT1 is the input setting.
For control valves with a linear flow curve it depends on the application. If LIN is selected for these valves a
significantly shorter deceleration distance can often be set (D:A and D:B).
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