Why are ST Language Loops Considered Harmful?

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 […]

Principles of Sequential Logic

Principles of Sequential Logic PLC Educative Solutions For Factory Automation

Sequential logic functions Sequential logic functions are time-dependent. They define the state of output variables according to the combination of input variables, and also by the memorised state of one or more variables. They are often synthesised by flip-flops. The interest of the sequential logic functions is demonstrated thanks to some examples. Basics of sequential […]

Automaton Properties

Automaton Properties PLC Educative Solutions For Factory Automation

IEC 63111-1 compliant PLCs, such as the PLC3000 solution, are characterised by a cycle operation. A cycle is generally composed of 5 phases: 1. reading inputs, 2. scanning the program, 3. writing outputs, 4. communication services, 5. internal functions. The scanning of the program is always done from top to bottom and from left to […]

Timer – LD

Timer – LD PLC Educative Solutions For Factory Automation

The IEC 61131 standart offers a definition of Timers. PLC3000 integrates only TON timers that can be set by defining the time base %Ti.TB, and the preset value %Ti.PV. The timer is triggered by activating the input %Ti.IN, and the output %Ti.Q goes to 1 when the current timer value reaches the preset value. The […]

Counter LD

Counter LD PLC Educative Solutions For Factory Automation

The IEC 61131 standard offers a definition of Counters. PLC3000 integrates up and down Counters. It is necessary to define a preset value %Ci.PV, which can be set with an integer value. The current value of a counter is set to 0 when %Ci.R is activated. The current value of a counter is set to […]

Programming in LD

Programming in LD PLC Educative Solutions For Factory Automation

1. Example in ST Let’s considering the logical equation: %M0 = %I0.%I1+%I2. /%I3 2. Example of Grafcet in ST Let’s considering the elementary Grafcet a. Programming Transition/Transition Initialization Test on Receptivity and Transition Crossing Output declaration b. Programming Transition/Transition with Crossing bits Initialization Test on Receptivity Transition Crossing Output declaration c. Programming Step/Step d. Programming […]

Instruction in LD

Instruction in LD PLC Educative Solutions For Factory Automation

Ladder (LD) is a visual programming language defined by the IEC 61131 standard. It includes components: Function AND – (X . Y) : |———| |—-| |———| X Y Function OR – (X + Y) : |——|—| |–|————| | X | |—| |–| Y Logical function – F=(X.Z + /Y) : |—|—| |—| |—|—-( )-| | […]