CompactLogix Project structure

Everything required for the program to function is contained within the project.

Controller organizer panel

Tasks The default project provides single task. A project can have up to 6-tasks. 1769-L32x processor. task holds information necessary to schedule the programs execution and determines the execution priority for one or more programs. Tasks

Continuous: The continuous task runs all of its programs, and then it starts again (continuously, you might call it). It’s quite normal to put most or all of your logic in the continuous task. Example; Fill a tank to its maximum value and then open a drain valve Periodic: Periodic tasks are scheduled to run at a pre-defined period, such as every 100 ms. Example; Read the thickness of a paper roll every 2 sec. Tasks

controller organizer tree By default, RSLogix 5000 has already created a continuous task called MainTask. Note the little circular arrow on MainTask – that means it’s a continuous task. Inside MainTask, it’s created a program called MainProgram, and it has one ladder logic routine called MainRoutine inside. It also has a place for program specific tags. These are tags that are only visible to logic inside of this program controller organizer tree

Program: Each task requires at least one program Program: Each task requires at least one program. A task can have up to 32-programs. Only one program can execute at-a-time. Main Routine: When a program executes the main routine executes first. The main routine is used to call(execute) other routines in the program (subroutines). The main routine in RSLOGIX 5000 is the same as LAD 2 in RSLOGIX 500. Routines: Routines are where the executable code resides. Routines can be written in: Ladder Logic, Sequential Function Chart, Function Block Diagram, and Structured Text. Routines are used to keep programs organized. Program

Tag Based Memory Structures Tag based memory structures are what most new generation PLCs use. A tag is a friendly name for a memory location. This tag name also has a data type assigned. Tag Based Memory Structures

The Scope of the tag defines if a tag is global (controller tags) and therefore available to all programs or local (program tags) to a select program group. Controller Tags are available to all programs. Program Tags are isolated from other programs. Tags

Compactlogix Tag Based Memory Structure

CompactLogix Tag Based Memory Structure Tag names should be assigned that are descriptive to the data being stored in them. Example of tag names could be: Start_PB, Vessel01MixMotor, furnaceTemp. CompactLogix Tag Based Memory Structure

Base Tag- Directly addresses a memory location. No special functions. Alias Tag- Points to an addressed memory location defined by another tag. Some common uses for Alias Tags are associating Base tags with Module Defined Input and Output tags. Tag

Data type Data Type Description Bits Possible Values BOOL                     Boolean or Bit         1           0 or 1 SINT                       Short Integer         8           -128 to 127 INT                         Integer                   16           -32,768 to 32,767 DINT                      Double Integer     32         -2,147,483,648 to 2,147,483,647 REAL                      Real Number        32         +/-3.402823E38 to +/- 1.1754944E-38 Data type

More data type Structure Data Type Type of Stored Data Timer Control structure for timer instructions counter Control structure for counter instructions Control Control structure for array instructions Message Control structure for the message instructions PID Structure for the PID instructions More data type