PLC Program Flow and Control Instructions
42mAdvanced2025-07-15
Authors
Zahraa Khalil
Engineering Instructor and Educator
Course details
Ladder logic is a common programming language used in industrial and manufacturing processes. The controller, using a programmable logic controller (PLC) program, specifies what action each device needs to perform. Many PLC operations follow linear sequences, but as you develop more complex applications, you also need to build more sophisticated logic into your projects. In this course, explore advanced PLC ladder logic programming instructions, including bit shift left, bit shift right, word shift operations, program flow control instructions, and subroutine instructions. Learn about first in, first out (FIFO) and last in, first out (LIFO) word shifting instructions, as well as other options (and how to choose from among them).
Skills covered
Ladder LogicElectrical EngineeringPLC Industrial Controls and ProgrammingHardwareProduct and ManufacturingOpen SourceDeep Dive (X:Y)
Concepts
0. Introduction
- 01 - PLC program flow and control
- 02 - What you should know before watching
1. Bit Shift Register
- 03 - Concepts of bits and words
- 04 - Bit shift registers intro
- 05 - Bit shift register parameters
- 06 - BSL instruction (bit shift left)
- 07 - BSR instruction (bit shift right)
- 08 - BSL instruction demonstration
2. Word Shift Operations
- 09 - Word shift operations intro
- 10 - First in, first out (FIFO) instruction
- 11 - FFL (FIFO load) parameters, part 1
- 12 - FFL (FIFO load) parameters, part 2
- 13 - FFU (FIFO unload) parameters
- 14 - Illustrate FIFO operation - Example
- 15 - Illustrate FFL operation, part 1
- 16 - Illustrate FFL operation, part 2
- 17 - Example program
3. Program Flow Control Instructions
- 18 - Intro to program control instructions
- 19 - Jump (JMP) to label (LBL) instructions
- 20 - Master control rest (MCR) instruction
- 21 - Difference between JMP and MCR
- 22 - Introduction to subroutines
- 23 - Jump to subroutine (JSR) instruction
- 24 - Subroutine (SBR) instruction
- 25 - Return from subroutine (RET)
- 26 - Nested subroutines
Conclusion
- 27 - Next steps