# Free Contents for Teaching PLC Programming

#### Counter – IL

The

**IEC 61131**standard offers a definition of Counters.**PLC3000**integrates up and down Counters. It is necessary to define a preselection value**, which can be set with an integer value. The current value of a counter is set to***%Ci.PV***when***0***is activated. The current value of a counter is set to the preselection value***%Ci.R***, when***%Ci.PV***is activated. The current value of a counter is incremented each time the***%Ci.LD***input is activated, and decremented each time the***%Ci.CU***input is activated. A counter has two outputs;***%Ci.CD***goes to***%Ci.QU***when the current counter ...***1*#### Timer – ST

The

**IEC 61131**standart offers a definition of Timers.**PLC3000**integrates only**TON**timers that can be set by defining the time base**, and the preset value***%Ti.TB***%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 time bases**%Ti.TB**that can be declared are: 10, 100 ms; 1, 10 s; 1 min.**Generation in ST**Let’s considering 3 timers with different time bases and preset valuesIF %S1 THEN %T0.TB := 100ms; %T1.TB := 1s; %T2.TB := 1min; %T0.PV := 3 ; %T1.PV := 2; ...#### Counter – ST

The

**IEC 61131**standard offers a definition of Counters.**PLC3000**integrates up and down Counters. It is necessary to define a preselection value**, which can be set with an integer value. The current value of a counter is set to***%Ci.PV***when***0***is activated. The current value of a counter is set to the preselection value***%Ci.R***, when***%Ci.PV***is activated. The current value of a counter is incremented each time the***%Ci.LD***input is activated, and decremented each time the***%Ci.CU***input is activated.A counter has two outputs;***%Ci.CD***goes to***%Ci.QU***when the current counter value ...***1*#### Timer – IL

The

**IEC 61131**standart offers a definition of Timers.**PLC3000**integrates only**TON**timers that can be set by defining the time base**, and the preset value***%Ti.TB***%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 time bases**%Ti.TB**that can be declared are: 10, 100 ms; 1, 10 s; 1 min.**Generation in IL**

Let’s consider three timers with different time bases and preset values LD %S1 %T0.TB := 100ms %T1.TB := 1s %T2.TB := 1min %T0.PV := 3 %T1.PV := 2 %T2.PV ...#### Edge Generation – IL

**PLC3000**does not include Rising and Falling Edge functions. However, they can easily be generated from the available memory bits

**Generation in IL**Generate a Rising Edge on

**%I0**is done by considering a memory bit,

*e.g.*

**%M1**, such as <img width="300" height="130" src="https://plc3000.com/wp-content/uploads/2021/05/FrontMontant-300x130.jpg" alt="" loading="lazy" srcset="https://i1.wp.com/plc3000.com/wp-content/uploads/2021/05/FrontMontant.jpg?resize=300%2C130&ssl=1 300w, https://i1.wp.com/plc3000.com/wp-content/uploads/2021/05/FrontMontant.jpg?w=533&ssl=1 533w" sizes="(max-width: 300px) 100vw, 300px" /> <pre> LD %I0 ANDN %M0 ST %M1 LD %I0 ST %M0

Generate a Falling Edge on

**%I1**is done by considering a memory bit, e.g.

**%M3**, such as

LDN %I1 ANDN %M2 ST %M3 LDN %I1 ST %M2 ...

#### Programming in ST

**1. Example in ST**Let’s considering the logical equation: %M0 = %I0.%I1+%I2. /%I3 PROGRAM LogicalFunction %M0 := %I0 AND %I1 OR %I2 AND NOT %I3; END_PROGRAM

**2. Example of Grafcet in ST**Let’s considering the elementary Grafcet

**a. Programming Transition/Transition**PROGRAM TrTr (* INIT *) IF %S2 THEN %M0 := TRUE; %M1 := FALSE; END_IF (* TRANSITIONS *) IF %M0 AND %I0 THEN %M1 := TRUE; %M0 := FALSE; END_IF IF %M1 AND %I1 THEN %M0 := TRUE; %M1 := FALSE; END_IF (* ACTIONS *) %Q0 := %M1; END_PROGRAM

**b. Programming Transition/Transition with**PROGRAM TrTrB (* INIT *) ...

*Crossing bits*#### Instructions in ST

The programming language

**(***Structured Text***ST**) is defined by the**IEC 61131**standard. It includes the instructions: := ; --> Assignment := TRUE; --> Assignment to 1 := FALSE; --> Assignment to 0 PROGRAM ... END_PROGRAM IF ... THEN ... ELSE ... END_IF FOR ... END_FOR WHILE ... END_WHILE Basic logic functions are: AND OR XOR: eXclusive OR and their complement are: AND NOT OR NOT XOR NOT : eXclusive AND Logic functions can be followed with parentheses: AND( OR( XOR( ) ) ) Comments can be added inside the symbols: (*…. *). The programming language includes two**types of ...**

#### Programming in IL

**c. Programming Step/Step**

* START LD %M1 AND %I1 OR( %M0 ANDN %I0 ) OR %S2 S %M0 R %M1 * LD %M0 AND %I0 OR( %M1 ANDN %I1 ) S %M1 R %M0 * ACTIONS LD %M1 ST %Q0

**d.**

**Programming Step/Step with*** START LD %M1 AND %I1 OR( %M0 ANDN %I0 ) OR %S2 ST %M10 * LD %M0 AND %I0 OR( %M1 ANDN %I1 ) ST %M11 * CROSSING LD %M10 S %M0 R %M1 * LD %M11 S %M1 R %M0 * ACTIONS LD %M1 ST %Q0

*Crossing**Bits***b. Programming Transition/Transition with**

...

*Crossing Bits*#### Instructions in IL

The programming language

**(***Instruction List***IL**) is defined by the**IEC 61131**standard. It includes the instructions: LD: LOAD ST: STORE S: SET R: RESET the set of basic logic functions: AND OR XOR: eXclusive OR and their complement: LDN: LOAD NOT ANDN: AND NOT ORN : OR NOT To the logic functions are associated with parentheses: AND( OR( XOR( ) ) ) Comments can be added after the symbol:*****...#### 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 ...