Extended Technical Overview

Portable IEC 61131-3 Control Applications

Additional detail on control structure, function block availability, and alignment with Open Process Automation and O-PAS principles — for control engineers, system architects, and automation decision-makers.

What the Library Is

The CSI Process Automation Function Library is a modular IEC 61131-3 control library implemented in CODESYS and developed as part of a structured roadmap toward alignment with Open Process Automation and O-PAS principles.

It encapsulates proven regulatory and supervisory control behaviors in a portable, vendor-neutral form that supports multi-vendor deployment, long-term lifecycle independence, and incremental modernization across DCS, PLC, and open control environments.

The library focuses on application portability and control behavior consistency. It does not constitute a complete O-PAS system and does not imply conformance or certification.

Function Block Availability

The table below distinguishes currently implemented function blocks from planned roadmap additions.

Available Now

Implemented

  • PID
  • Control Selector (CS)
  • Output Splitter (SPLT)
  • Integrator (INTG)
  • Analog Input (AI)
  • Analog Output (AO)
  • Discrete Input (DIN)
  • Discrete Output (DOUT)
Roadmap

Coming Soon

  • Bias / Gain
  • Dead Time
  • Lead–Lag
  • Ramp Generator
  • Signal Characterizer
  • Input Selector
  • Ratio
  • Manual Loader
  • NAMUR PID
  • Timer

Planned items reflect current roadmap intent and may evolve.

Control Strategy Examples

Cascade Control Loop

Cascade control improves disturbance rejection by separating fast inner-loop dynamics from slower outer-loop objectives, enabling more stable and responsive control across changing conditions.

Override and Constraint Handling

Selector-based constraint handling arbitrates between competing process objectives without modifying underlying controller logic, supporting safer operation during limits, trips, and abnormal conditions.

Alignment with OPA

  • IEC 61131-3 used as the canonical application layer
  • Separation of control logic and execution environment
  • Application portability across hybrid and evolving architectures
  • Incremental adoption aligned with O-PAS principles
  • Roadmap-aligned, not positioned as certified

Where This Is Used

  • OPA pilot programs
  • Brownfield modernization initiatives
  • Hybrid DCS and open control environments
  • Multi-vendor automation strategies

Discuss your control architecture with CSI

CSI is an independent systems integrator specializing in advanced process control and open, vendor-neutral automation architectures.

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