Definition of terms for transitions, actions and conditions¶
Comments to the picture¶
- Marker 1: Boolean expression in a condition for a Continuous action with assignation condition.
- Marker 2: A Boolean symbol is written by a Stored action on activation.
- Marker 3: An analog symbol is written by a Stored action on activation.
- Marker 4: A BOOL symbol for a Continuous action.
Write an analog symbol¶
A analog symbol can be written with a Stored action
Notes:
- Arithmetic operations: addition (+), subtraction (-), multiplication (*) and division (/).
- If you divide by zero, the result is set to the maximum value of the data type.
Info
The expression is calculated from left to right. Point-before-bar calculation must be prioritized with brackets.
Examples:
Assignment | Remarks |
---|---|
AO0:=100 | The value 100 (decimal) is written to the analog symbol AO0. |
AO0:=Value1 | The value of Value1 is written |
AO0:=AO0+1 | There is written the result of AO0+1 |
AO0:=Value1 + Value2 | The result of the addition is written |
AO0:=Value1 * Value2 | The result of the multiplication is written |
AO0:=Value1 + Value2 - Value4 | etc. |
AO0:=Value1 * (Value2 + Value3) | etc. |
AO0:=Value1 * (Value2 * (Value3*Value4)) / Value5 | etc. |
Boolean expression¶
A Boolean expression must be specified in transitions and Action conditions. See marker 1.
Notes:
- Possible binary operations: AND (*), OR (+)
- Modifiers: Rising edge (↑), Falling edge (↓), Negation (!)
- Comparisons can be combined with AND, OR.
Info
A comparison must always be made in square brackets (see examples below).
Info
In the Boolean expression '*' causes a AND operation and a '+' causes a OR operation.
Info
The expression is calculated from left to right. AND- before OR must be prioritized with parentheses
Examples for Boolean expressions:
Boolean expression | Comments |
---|---|
I2 | Only a boolean symbol is specified. |
I0*I1 | AND conjunction between two Boolean symbols |
I0+I1 | OR conjunction between two Boolean symbols |
I0*I1*(I2+I3) | AND and OR combination with parentheses |
(I0*I1)+(I2*I3) | The result of two AND conjunctions are OR combined |
↑I0 | Rising edge of I0 |
↓I0 | Falling edge of I0 |
!I0 | Negated query of I0 (Will be displayed by a horz. line in Grafcet) |
↓I0*I1 | Falling edge of I0 AND I1 |
2s/(I0*I1)+I2 | If I0 AND I1 are TRUE, a time starts (2 sec.). The expression is TRUE if I2 is TRUE OR the time is expired and I0 and I1 are still TRUE |
I0*[Value1>Value2] | I0 must be TRUE and Value1 must be greater than Value2. Comparators must be in square brackets. |
I0*[Value1>Value2+10] | I0 must be TRUE and Value1 must be greater than Value2+10. This example also makes it clear why a comparison must be in square brackets. The plus sign is an addition within the parenthesis and an OR conjunction outside the parenthesis. |
[Value1>Value2] * [Value3<Value3] | An AND conjunction of two comparators. |
[Value1=Value2] | Comparison on equal |
[Value1!=Value2] | Comparison to different |
[Value1>Value2] | Comparison on bigger |
[Value1<Value2] | Comparison to less than |
[Value1>=Value2] | Comparison on greater than or equal to |
[Value1<=Value2] | Comparison on less than or equal to |
Write a Bool-Symbol¶
A Boolean symbol can be written with a stored action. See marker 2
Syntax:
Bool-Symbol:=Boolean expression
Explanation of Boolean expression (see above).
Grafcet-Studio and the Standard DIN EN 60848¶
This Grafcet features are not yet supported by Grafcet-Studio:
- ~~Forcing of a partial Grafcet to the current situation (Freeze command)~~
- Edge of a bracket term. Sample: ↑(I0*I1). Edge of operands are possible: ↑I0
- ~~Time limited action: This is not supported !(6s/X28) in a continuous action with condition.~~
- Query of step duration. Example for step "1"="T1" (../See DIN EN 60848[22])