LD UDFB Guided Learning Q15: – Modify the state machine to drive a dual-coil DCVA

Automation and Control
1

This article is part of a guided learning series on building and analyzing User-Defined Function Blocks (UDFBs).

:pushpin: Canonical Article: Building a User-Defined Function Block (UDFB) Using Siemens TIA Portal
:blue_book: Learning Companion (Q&A): Explore All Questions

You are reading: Question 15

Modify the state machine to drive a dual-coil DCV.

Clarification

A pneumatic or hydraulic Directional Control Valve (DCV) requires a state machine similar to the featured motor starter.

Answer

This is left as a design exercise for advanced students.

To get started, let’s assume a dual-coil DCV with magnetic detection sensors for full cylinder extension and retraction.

  • Use descriptive state names: retracted, extending, extended, retracting, and fault.
  • Incorporate both the extended and retracted sensors into the UDFB:
    • xSenExtended is monitored for states extending and extended.
    • xSenRetracted is monitored for states retracting and retracted.
  • Add appropriate time delays to account for the slower physical motion of the pneumatic or hydraulic cylinder.

:writing_hand: Article by Aaron Dahlen, LCDR USCG (Ret.), Application Engineer at DigiKey