Yaskawa MP900 Series Ladder Programming Manual - Manual (Page 44)

4.2 Ladder Drawings
4.2.1 Types of Ladder Drawings
4-3
Programming
4
4.2 Ladder Drawings
Ladder programs are managed as drawings (ladder drawings) that are identified by their drawing numbers (DWG
numbers).
The ladder drawings form the basis of the ladder programs.
4.2.1 Types of Ladder Drawings
( 1 ) Types and Priorities of Drawings
There are the following types of ladder drawings: parent drawings, child drawings, grandchild drawings, and operation
error drawings.
• Parent Drawings
These drawings are automatically executed by the system when the execution conditions that are listed in the fol-
lowing table are met.
• Child Drawings
These drawings are executed when they are called from a parent drawing with a Call Program (SEE) instruction.
• Grandchild Drawings
These drawings are executed when they are called from a child drawing with a Call Program (SEE) instruction.
• Operation Error Drawings
These drawings are automatically executed by the system when an operation error occurs.
There are also five different types of drawings based on their role.
The following table gives the priority and parent drawing execution conditions for each type of drawing.
∗ Drawings with lower numbers have higher priority.
The breakdown of the number of drawings in each category is given in the following table.
Priority* Drawing Type Role Parent Drawing Execution Condition
Maximum Number
of Drawings
1 DWG.A
Startup
processing Power ON
(Processed once when the power supply is turned ON.)
64
2 DWG.I
Interrupt
processing
External interrupt
(Executed when a DI interrupt or counter match inter-
rupt is received from an Optional Module.)
64
3 DWG.H
High-speed scan
processing Started at fixed intervals.
(Executed every high-speed scan.)
200
4 DWG.L
Low-speed scan
processing Started at fixed intervals.
(Executed every low-speed scan.)
500
– Functions User functions
Function call
(Executed when called with a FUNC instruction from a
drawing.)
500
Drawing
Number of Drawings
DWG.A DWG.I DWG.H DWG.L
Parent drawings 1 drawing 1 drawing 1 drawing 1 drawing
Operation error drawings 1 drawing 1 drawing 1 drawing 1 drawing
Child drawings Total of 62
drawings max. Total of 62
drawings max. Total of 198
drawings max. Total of 498
drawings max.
Grandchild drawings