ISPSoft User Manual

Chapter 12 Sequential Function Chart
If the programming language used to create a transition program is a structured text, there is no limit
on the number of lines of program code. However, a Boolean state in a transition program must be
assigned to a symbol name which is the same as the transition program name.
If the programming language used to create a transition program is a function block diagram, the
program code of the transition program must be composed of one network, and the output contact
must be assigned a symbol name which is the same as the transition program name. Besides,
multiple outputs are not allowed in a transition program created by means of a function block
diagram.
If the programming language used to create a transition program is an instruction list, there is no
limit on the number of lines of program code. OUT, SET, RST, and applied instructions can not be
used in a transition program created by means of an instruction list. Besides, the output instruction
in a transition program created by means of an instruction list must be TRANS, and the operand for
TRANS must be assigned a symbol name which is the same as the transition program name.
When users create a transition program, a symbol name which is the same as the transition
program name is added to the program code of the transition program. The users only have to
create a conditional operation. Owing to the fact that the actions and the transitions in a sequential
function chart share the same local symbol table, there are not local symbol tables in the program
editing windows for the transitions.
Users can not create a complex transition program. If a transition condition must undergo a complex
operation, users can create the complex operation in an action associated with a step, create a
condition flag in the action, and assign the flag to the transition following the step.
Although users do not need to declare the symbols in the transition programs, the system assigns
memories which function as flags to the symbols. As a result, users have to make sure that the
symbols in the transition programs can be assigned a specific logic state. Otherwise, an error will
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