Omron NX1P, Programming Manual

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3-8 Fundamentals of Programming to
Reduce Development Time
3-8-1 POUs (Program Organization Units)
 POUs
A POU (program organization unit) is a unit that is defined in the IEC
61131-3 and used to build the user program. There are three types of
POUs: programs, functions (FUNs), and function blocks (FBs).
FUNs and FBs that are reusable software components make
programming easier.
3-8-2 Programs and Execution Priorities (Tasks)
 Programs
Separate programs for different processes make programs easy to read and reuse.
Two different programming languages, ladder diagram and ST, can be used. You can
choose the appropriate language for each process and also program in ST within a ladder
diagram program (inline ST).
 Tasks
A task is an attribute that defines when a program is executed. You
can set a task period for each program.
To execute processes with high speeds, assign the program to the
primary periodic task that has the highest execution priority.
By assigning processes that do not require high-speed processing to
the task that has the lower execution priority, you can reduce the load
on the NX1P. One or more programs can be assigned to one task.