Pous In Ispsoft; Managing The Tasks In Ispsoft - Delta AH Series Operation Manual

AH M o ti on Co n tro l ler – Op era tion Ma nua l
7.2.2

POUs in ISPSoft

All POUs created by users are listed in the program management area. The POUs of the program type and the POUs of
the function block type are managed separately. Besides, the programming language in which a POU is written
determines the icon representing the POU, and the information about the POU is put at the end of the POU name.
After a POU in the project management area is double-clicked, a POU editing window will appear. The POU editing
window is composed of two parts. A table of local symbols is at the upper part of the window, and the body of a program is
at the lower part of the window. Besides, the editing environment at the lower part of the window varies with the
programming language used. Please refer to the following sections for more information about symbol tables and program
editing.
7.2.3

Managing the Tasks in ISPSoft

In ISPSoft, not all the POUs of the program type in the project are executed. A POU of the program type will be executed
after it is assigned to a task, and the task determined how the POU is executed. If a POU is not assigned to a task, the
POU will be taken as a general source code, will be saved with the project, and will not be translated into an execution
code. Besides, only POUs of the program type need to be assigned to tasks, and function blocks are called by POUs.
In ISPSoft, a POU of the program type is assigned to a task. However, more one POU can be assigned to the same task,
and the order in which these POUs are executed can be specified. Besides, after you add a POU of the program type, you
must assign it to a default task.
There are three types of tasks. They are cyclic tasks, timed interrupt tasks, and conditional interrupt tasks.
 Cyclic task
A POU assigned to a cyclic task is scanned back and forth. There are 32 cyclic tasks in a project for an AH series CPU.
These cyclic tasks are numbered from 0 to 31. The smaller the task number is, the earlier the task is executed. Besides,
AH series CPUs support the API (applied instructions) TKON and TKOFF which control tasks. You can enable or disable
a task during the operation of an AH series CPU.
A POU is which a sequential function chart can only be assigned to a cyclic task. It can not be assigned to an interrupt
task.
 Timed interrupt task
A POU of the program type which is assigned to a timed interrupt task is like a timed interrupt subroutine. If the time when
timed interrupts should occur is reached, the POUs assigned to the timed interrupt task will be executed in order. Besides,
the number of timed interrupt tasks depends on a PLC selected. The number of interrupt triggers that a PLC supports is
the available number of timed interrupt tasks that can be used in the software.
 Conditional interrupt task
_7
There are several types of conditional interrupt tasks. For example, external interrupts, I/O interrupts, counting interrupts,
and etc. Different PLCs provide different conditional interrupt tasks. You have to make sure of the conditional interrupt
tasks which are supported by the PLC before you assign the POUs of the program type to tasks. A POU of the program
type which is assigned to a conditional interrupt task is like an interrupt subroutine. If the condition of an interrupt is met,
e.g. the value of a counter reaches the setting value, the POUs assigned the interrupt task will be executed in order.
7 - 4