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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
Instruction List (IL) is a low-level programming language, which is analogous to assembly language. Like assembly language, IL uses mnemonic commands that execute directly. Also, like assembly, IL is the lowest-level language where there is a direct correspondence between program statements and the processor’s machine-code instructions. As a non-interpretive programming language1, the Assembly program must be compiled into machine code to operate, which is the digital language understood by a computer. Beyond assembly language is machine code, itself. Machine code uses built-in instruction sets, which are patterns of bits that by the digital-circuit design can be executed directly by a CPU to perform very specific tasks. Machine code looks like a stream of 1s and 0s. Machine code might use 8-bit words, for instance, where the first four bits represent an instruction, called opcode, and the second four bits contain the operand, or in simpler terms, the data. Although it may be possible to write code in machine language, it would be very tedious and prone to errors, so an assembly-type language, like instruction list, would provide a more practical alternative to machine code.
Advanced Digital Concepts
Published in Dale Patrick, Stephen Fardo, Vigyan ‘Vigs’ Chandra, Electronic Digital System Fundamentals, 2020
Dale Patrick, Stephen Fardo, Vigyan ‘Vigs’ Chandra
The main components of a microprocessor are shown in Figure 11-6. Note the timing and control unit determines the sequence in which operations must occur in the processor. Use is made of the Interrupt controller and the I/O controller for connecting to external devices. Programs are fetched from memory making use of the bus controller which sets the proper memory address on the address bus, and fetches the data using the data bus. The program counter keeps track of the instruction being executed using the instruction register and decoder generates the proper sequence of machine code cycles corresponding to any instruction.
Computer Programming
Published in Quamrul H. Mazumder, Introduction to Engineering, 2018
Machine code is the basic low-level programming language designed to be recognized by a computer. The language is composed entirely of binary code or long sequences of 0s and 1s that represent on and off electric impulses. Each binary instruction is composed of multiple binary digits. A program can have hundreds of thousands or even millions of binary instructions, and writing such a program would be tedious and time consuming. Misplacing a single 0 or 1 digit will cause an error in the program.
Prediction of scour depth at piers with debris accumulation effects using linear genetic programming
Published in Marine Georesources & Geotechnology, 2020
The LGP is a developed version of conventional GP, which was first introduced by Koza (1992). The LGP is a variant of GP with a linear instruction of individuals in which evolves in a programming language C/C++ as a substitute for the expression of a functional language in GP (Alavi, Gandomi, and Gandomi 2010). Figure 3 depicts a comparison of the structures in tree-based GP and LGP. The proposed method is developed using the automatic induction of machine code by GP (AIMGP), where the solutions are directly calculated as linear strings of machine code and implemented without applying an interpreter, accordingly the computer program can be run notably faster than the GP method (Brameier and Banzhaf 2001; Foster 2001). Generally, the four steps needed to solve a problem by LGP are given as follows:
Speeding Up Monte Carlo Computations by Parallel Processing Using a GPU for Uncertainty Evaluation in accordance with GUM Supplement 2
Published in NCSLI Measure, 2018
C. M. Tsui, Aaron Y. K. Yan, H. W. Lai
After the GUM Supplements were published, numerous software tools were developed to adopt MCM in uncertainty evaluations. One example is an in-house software tool used in the Radio Frequency Laboratory of SCL for evaluation of uncertainties involving complex quantities such as S-parameters [4]. The tool was written in Visual C++ and Visual Basic for Application (VBA), with Microsoft Excel as front-end user interface. As MCM involves large number of repetitive computations, the processing time of this old SCL software tool (the old tool) is long especially for complicated measurement models. The old tool is slow for two reasons. Firstly, the VBA program is interpreted by a virtual machine and is not compiled into native machine code that will be executed faster by the central processing unit (CPU). Secondly, the VBA program is single-threaded, which will not utilize more than one CPU core. The meaning of “thread” may vary between different computer systems but it may loosely be described as a single CPU process. The commands in a single-threaded program are executed sequentially and will not be sped up even if the computer has multiple parallel processors.