IEC 61131-3 Math and Logic Editors

Intuitive PLC-Like Programming


Five IEC 61131-3 Programming Interfaces

IEC 61131-3 is the international standard for programmable logic controller (PLC) programming languages and specifies the syntax, semantics and display for five languages. Multiple language support in IEC 61131-3 enables the control program developer to select the language that is best suited to a particular task.

“Working with OrionLX as a part of my Masters thesis (at Colorado State University) has been both a technically rewarding and industry-valued experience. With its built-in ‘Advanced Math & Logic’ engine software and Modbus TCP communication protocols (among many others), the OrionLX DA controller proved to be an efficient and user-friendly component for my power systems hardware-in-loop simulations/set-up.”

– Abhishek Jain, PhD Candidate in Electrical and Computer Engineering at North Carolina State University

Programming Interfaces

Ladder Diagrams (LD) Traditional PLC “Ladder Logic”
Function Block Diagrams (FBD) Uses “functions” between input variables and output variables
Structured Text (ST): a text-based high level language that syntactically resembles Pascal. Complex statements and nested instructions are supported: Iteration Loops (REPEAT-UNTIL; WHILE-DO), Conditional Execution (IF-THEN-ELSE; CASE), Functions (SORT(), SIN())
Instruction List (IL): an efficient, text-based, low level language that resembles assembly
Sequential Function Chart (SFC): A language to model complex programs such as DA scenarios with second contingencies, load-checking and multiple alternate sources. The SFC program is made up of sections of logic developed in the languages above (“Steps”), connected to other Steps by conditions which must be fulfilled before proceeding (“Transitions”). Steps can be processed sequentially and in parallel.

Full Integration with NCD

Orion IEC 61131-3 is fully integrated in the Orion NCD (NovaTech Configuration Director) configuration software. All points and records accessed from IEDs by Orion (SCADA data, fault data from SEL® Short Event Summaries, etc.) or points generated internally (diagnostic data, comms data, etc.) are available for use in OrionLX IEC 61131-3 math and logic schemes.

Offline Simulation and Secure Online Viewing of Logic Execution

OrionLX IEC 61131-3 includes an offline simulator to view logic execution exactly as it will appear when running online in the OrionLX.

Screen Captures


Ladder Diagram


Instruction List


Sequential Function Chart


Structured Text


  • NovaTech Utility Systems and Services

    Almost half of NovaTech’s business is in Systems and Services including web page design, panel design, math and logic development, Orion configuration, and onsite installation and commissioning. Mark Matassa explains how our engineers can work with you to reduce project execution time at the 2016 DistribuTECH Conference and Exhibition in Orlando, Florida.

    March 18, 2016

  • Math and Logic Processor

    The OrionLX or OrionLXm can serve as a substation Math and Logic Processor. Data polled from attached IEDs – meters, event recorders, I/O, relays, breakers, etc – can be manipulated using the OrionLX internal Math and Logic Functions.

    September 17, 2014

  • OrionLX IEC 61131-3 Math & Logic Webinar

    A webinar covering the five Math and Logic toolkits in IEC 61131-3: Ladder Diagram, Structured Text, Function Block Diagram, Sequential Function Chart, Instruction List, and how each application should be used.

    February 1, 2013

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