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Basics of PLC Programming - Coggle Diagram
Basics of PLC Programming
Processor Memory Organization
Program Files
System functions (File 0)
Reserved (File 1)
Main ladder program (File 2)
Data Files
Output (File 0
Input (File 1)
Status (File 2)
Memory Types
Rack-based system
Tag-based system
Fixed/variable memory segmentation
Program Scan
Scan Cycle
Input scan
Program scan
Output scan
Scan Time Factors
Processor speed
Program length
Type of instructions
Data Flow
Input image table
Output image table
oLogical evaluation
PLC Programming Languages
Ladder Diagram (LD)
Rung-based logic
Contact-coil representation
Relay-like structure
Function Block Diagram (FBD)
Block-based logic
Data flow representation
Boolean logic gates
Sequential Function Chart (SFC)
Steps and transitions
Parallel processing
Flowchart-like logic
Relay-Type Instructions
Examine If Closed (XIC)
Normally open contacts
Evaluates for logical 1
Examine If Open (XIO)
Normally closed contacts
Evaluates for logical 0
Output Energize (OTE)
Acts like a coil
Activated by rung continuity
Instruction Addressing
I/O Address Format
Input file (I)
Output file (O)
Status file (S)
Allen-Bradley Addressing
Slot-based format
Bit-level identification
Memory Mapping
Bit addressing
Word addressing
Integer and floating-point storage
Branch Instructions
Parallel Input Branches
OR logic representation
Multiple inputs activating one output
Parallel Output Branches
One condition activating multiple outputs
Nested Branches
Avoiding redundant instructions
Enhancing program efficiency
Internal Relay Instructions
Internal Outputs
Stored in bit files (B3 in SLC 500)
No direct connection to physical outputs
Using Internal Relays
Reduce physical output usage
Improve scan time
Addressing Internal Relays
Bit-file-based addressing
Used in nested logic
Entering the Ladder Diagram
Programming Interfaces
RSLogix 500 software
Handheld programming devices
Handheld programming devices
Ladder Diagram Development
Drag-and-drop logic blocks
Toolbar-based instruction placement
Address assignment methods
Common Screens in RSLogix
Main programming window
Instruction toolbar
Data file management