Toshiba T2N - Manual (Page 155)

2. User Program Configuration
142 PROSEC T2N
The user program is composed of each of the program types of main
program, sub-program #1, interrupt program (Timer and I/O #1-#4 ) and
sub-routines. Of these program types, a main program must always be
present. However, the other program types may not be present at all if
they are not used. Therefore, needless to say, a user program can be
configured with a main program only.
Also, among the program types, the programs can be divided into units
called ‘blocks’. Block division is required in the following cases.
* When using languages other than ladder diagrams (1 language/
block)
* When creating multiple SFC programs (1 SFC/block, see Section
5.3)
* When block division by control function units makes the program
easier to see.
There are no restrictions on program capacities (numbers of steps) by
program types and blocks. (Except in the case of SFC)
As block numbers, 1 to 256 are available. However, the block numbers
need not be consecutive. When executing the program, the program is
executed in sequence from the block with the lowest number.
In programming, the program type and block number is designated by
the program read function of the programmer, and the specified portion
is displayed on the screen. Then, the required program editing can be
performed.
Whether it is possible to use ladder diagram and SFC is shown below
by program types.
Program Type Ladder SFC
Main program Yes Yes
Interrupt program Yes No
Sub-program Yes No
Sub-routine Yes No
2.3
User Program
NOTE