7.1 User Program Types and Execution Timing
7.1.1 Ladder Programs
7-4
Hierarchical Configuration
There are four types of ladder drawings: parent drawings, child drawings, grandchild drawings,
and operation error drawings.
•
Parent Drawings
These drawings are automatically executed by the system program when the execution con-
ditions are met.
•
Child Drawings
These drawings are executed when they are called from a parent drawing with a SEE instruc-
tion.
•
Grandchild Drawings
These drawings are executed when they are called from a child drawing with a SEE instruc-
tion.
•
Operation Error Drawings
These drawings are automatically executed by the system program when an operation error
occurs.
A parent drawing cannot call a child drawing from a different type of drawing. Similarly, a child
drawing cannot call a grandchild drawing from a different type of drawing. A parent drawing
cannot call a grandchild drawing directly. The parent drawing first must call the child drawing,
and then the child drawing must call the grandchild drawing. This is called the hierarchical con-
figuration of drawings.
The following figure shows the parent−child−grandchild structure in which a program is cre-
ated.
DWG.
DWG.
01
Note: 1.
= A, I, H, L
DWG.
nn
DWG.
01.01
DWG.
01.02
FUNC-001
FUNC-006
FUNC-0
3
2
FUNC-064
DWG.
01.0
3
U
s
er Function
s
Grandchild Drawing
s
Child Drawing
s
Parent Drawing
DWG notation: DWG.
.
DWG.
00
Fixed value (00)
Parent drawing type (A, I, H, or L) of the drawing where the error occur
s
Child drawing number
Parent drawing type (A, I, H, or L)
Grandchild drawing number
2. The following notation i
s
u
s
ed for operation error drawing
s
.
