Ladder Logic Components
There are some Ladder logic components given below :
Rail and Rung
Vertical lines are called rails and the horizontal lines are called rungs.
Concept of NO/NC switch
NO(Normally Open) and NC(Normally Closed) are used to represent the state of current flow or contact in electronics circuit, which is also used is PLC ladder logic programming. These terms define whether the switch is open or closed.
Normally Open
- A normally open switch or contact is open when not actuated.
- It closes the circuit when pressed or activated, allowing current flow.
- In ladder logic diagrams, a normally open contact is shown as an open gap and becomes a solid line when activated.
Normally Closed
- Normally closed switch/contact is closed when not actuated.
- Activation of the switch opens the circuit, stopping current flow.
- In ladder logic diagrams, it’s represented as a solid line, becoming an open gap when activated.
Switch and Their Output
Output/Coil
Output devices are such as motor, valve, indicator, lights etc. but in LLD it is represented by vertical line with a label representing the output device.
PLC Programming Ladder Logic
A PLC or Programmable Logic Controller is a special type of digital computer without a monitor and keyboard. This is basically used in industrial automation such as manufacturing, automotive, food and beverage, chemical processing, and more to automate systems. This tiny computer receives data through input and sends operating instructions as output.
As the name suggests, it’s a programable device. The main languages that are used to program a PLC are ‘Ladder Logic’ and ‘C’. Ladder Logic is the most used programming for PLCs.
Table of Content
- Ladder Logic
- Ladder Logic Structure
- Ladder Logic Components
- Description and Working
- Advantages an Disadvantages
- Applications
- Examples