Toshiba Programmable Logic Controller V200 - Manual (Page 119)

Page 111
Mode I/O Timer Main program
7.5 User Program
The user program is stored by each program types as shown in the following diagram and is managed by units
called blocks in each program types.
User program configuration Program type internal configuration
(Program types) (Blocks)
Main program
Block 1
Sub-program #1
Block 2
Timer interrupt
I/O interrupt #1
Block 10
I/O interrupt #2 Block N
(N = max. 256)
Subroutine
Block 1
In the user program, the main program is the core. The scan operation explained is for the main program. The
operation of other program types are explained in the following sections:
The following 6 program types are supported by the V200 .
(1)……..Main program
(2) Sub-program #1
(3) Timer interrupt program
(4) I/O interrupt program #1
(5) I/O interrupt program #2
(6) Subroutine
The blocks are just separators of the program, and have no effect on the program execution. However, by dividing the
user program into some blocks, the program becomes easy to understand. The block numbers need not be con-
seductive. In each program type and block, there is no limit of program capacity. The only limit is the total capacity.
7.5.1 Main Program
The main program is the core of the user program. It is executed once in each scan.
1 scan time
Mode I/O Timer Main program
In the above figure,
Time
Mode means the mode control operation
I/O means the I/O update processing
Timer means the timer up date processing
Main program means the main program execution
the self-diagnostic check and peripheral support are omitted in this figure.
The end of the main program is recognized by the END instruction. Although instructions may be present after the
END instruction, that portion will not be executed.