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IEC 61131-3 PLC programming languages (LD, FBD, SFC, ST, and IF)
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
Function Block Diagram (FBD) is a graphical language, where the instructions are grouped into blocks that emulate Boolean algebra functions coupled with other mathematical and control-function blocks. Some functions are pre-defined and available from within the programming language, while others are user-defined, and can reach any level of complexity. Technically, all PLCs’ built-in instructions, such as the Timer-On (TON), Limit Test (LIM), or the Scale with Parameters (SCP) instructions are pre-defined function blocks. The concept of using function blocks is to pass input data through a Boolean-like decision tree of logical, mathematical, and control instructions to produce outputs, using a visually based language. Some people believe FBD programming is more intuitive for technicians who do not have a good background in relay logic. Others believe that plant designs should be done by engineers, and the programming should also be done by the engineers who thoroughly understand the systems, rather than computer specialists, and that either LD or FBD programming is equally easy for an engineer. For that matter, ST routines to simplify mathematical computations should also be easy for an engineer, and when it is available, it should be used to simplify LD and FBD programs, and to perform complex mathematical operations.
Basic Programming Principles of PLCs
Published in Stamatios Manesis, George Nikolakopoulos, Introduction to Industrial Automation, 2018
Stamatios Manesis, George Nikolakopoulos
Because there is not a generally established translation of the FBD language, it is possible to refer to this with the terms “logic components language”, “logic diagram language”, “logic gates language”, and other similar terms. Literally, the function block diagram language contains symbol blocks of functional operations, which implement various functions from the simple AND function from Boolean algebra up to PID control. Every block has the name of the function that it implements and accepts on the left side the inputs and on the right side the output, which carries the result of the function as presented in Figure 7.2. In fact, both the inputs and the outputs contain an additional set of assistive functions, for example the output ENO of the block ADD_I for adding integers, that inform us if the result is out of limits.
Ethernet for Control Automation Technology
Published in Richard Zurawski, Industrial Communication Technology Handbook, 2017
Gianluca Cena, Stefano Scanzio, Adriano Valenzano, Claudio Zunino
Two textual and three graphical languages are included in the IEC 61131-3 standard: Instruction list (IL) is a low-level programming language, with a level of abstraction similar to assembler.Structured text (ST) resembles high-level programming languages like C or C++.Ladder diagram (LD) allows to represent the program as a sequence of digital circuits, including contacts, coils, and specific blocks like counters, timers, etc.Function block diagram (FBD) is based on block diagrams, where blocks are connected through oriented arcs. It describes how inputs, through the blocks, are transformed into outputs.Sequential function chart (SFC) represents the control program as a sequence of states (steps) with associated actions activated by given conditions (transitions).
A Bio-Inspired, Self-Healing, Resilient Architecture for Digital Instrumentation and Control Systems and Embedded Devices
Published in Nuclear Technology, 2018
Shawkat S. Khairullah, Carl R. Elks
International Electrotechnical Commission (IEC) 1131 is a widely used de facto standard for programmable logic controllers (PLCs) and I&C systems. The purpose of IEC 1131 is to support a standard programing model for PLCs. Among the programming models endorsed by IEC 1131 is the Function Block Diagram language; these standards define the operational semantics for each FB in the program.19,20 In BioSymPLe, we decided early on to adopt the concept of the function block programming model to facilitate portability to the PLC and digital automation community. While our function blocks are not semantically equivalent to IEC 1131, our AFB model is closely related to the semantics of IEC 1131 and IEC 61499 (e.g., distributed function block programming standard). The proposed AFB shown in Fig. 5 is built based on our previous work21,22 on the concept of PLCs, and it is divided into three divisions: control flow, 1131-based data flow, and LUT-based data flow.
Automation and control of the thermal mixing process
Published in Systems Science & Control Engineering, 2023
L.C. Parra-Camacho, A.F. Rodriguez-Bayona, J.J. Carreno-Zagarra
The Function Block Diagram (FBD) programming language described in Commission (2003) is a restricted graphical representation of the machine-orientated language Instruction list (IL) with common logical block operators (AND, OR, NOT…). Ausberger et al. (2020) and Pavlovic and Ehrich (2010) It was used for programming HC900 Honeywell DCS through Designer Software, adapting the logic made in Grafcet and dividing the FBD into different sections (Inputs, outputs, A1, F1, F2…), making its read easier.