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Why are ST Language Loops Considered Harmful?

The Structured Text (ST) language is among the languages of the IEC 61131 standard supported by PLC3000. Compared to other languages like Instruction List (IL), ST supports expressions with a higher level of abstraction. It notably provides loop statements. However, the use of loops is generally considered a poor practice when programming programmable logic controllers […]

Loops – ST

The Structured Text (ST) language supports 3 kinds of loops: FOR … DO … END_FOR: Reapeats some processing for some given iteration count WHILE … DO … END_WHILE: Repeats some processing while a condition is true REPEAT … UNTIL … END_REPEAT: Performs some processing at least once, then repeats it until some condition becomes true […]

Mnemonics in the IL Language

At each variable can be associated a mnemonic. It is then possible to use the mnemonic or variable completely transparently in programs. To associate the variable Switch to the input %I0, the variables RedLight and GreenLight to the outputs %Q0 and %Q1 respectively, it is necessary to write: %I0 Switch %Q0 RedLight %Q1 GreenLight

System Bits

PLC 3000 has 2 system bits: %S1: for the initialization and setting of timers and counters, %S2: for the initialization of the memory bits. These system bits correspond to Rising Edges correlated to the RUN of the Code and the Reset of the scale models.

Getting Started

Functionalities of PLC3000 are accessible from the exercise catalog, with a login and password. The user is granted access to an index of themes and exercises presenting a sequence in the learning of Automation and Grafcets implementation according to the IEC 61131 standard. Access to each exercise is very easy via navigation between the different […]

What is PLC 3000?

PLC3000 is an intuitive tool for coding and simulating Programmable Logic Controllers (PLCs) with various interactive scale models. It has the advantage, from the user’s point of view, of using only one page on a web browser. From this web page, the user has access to the exercise topics, to the visualization of the educational […]