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Programmable Logic Controls training day 2
The document discusses the basics of ladder programming for PLCs. It covers logic diagrams, contact and coil symbols, AND and OR gates, conditional logic, ladder diagrams, outputs and latches. Examples are given for conditional logic statements and exercises are provided to write programs to implement those statements using PLC ladder logic. Timers and counters are also introduced.
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Programmable Logic Controls training day 2
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- 2. PLC Training Day2 Ladder Programming
- 3. Basics • Observe thediagram below
- 4. Other Symbols inLogic Diagrams Normally Open /Closed Contact Normally Open/ Closed Coil Timers
- 5. Normally Open/ ClosedContact
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- 7. Basic AND &OR Gates AND Gate OR Gate
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- 11. Outputs and Latches •These can be used as conditions for other actions • For instance, an output can actuate another sequence of events
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- 14. Exercise Write a PLCprogram to implement the conditional logic statements (a), (b) and (c) below. a) A PLC output is to switch on if any of three inputs is switched on. b) A PLC output is to switch on if any one of three inputs is switched on but not two or more. c) A PLC output is to switch on if any two outputs are switched on, but not the third.
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- 17. Implementing Latching • Whatdoes the term Latching mean ?
- 18. Timers • Timers areused to implement timing functionality in PLCs. • Most basic use is to introduce delays between processes
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Editor's Notes
- #4 The logic of the rung above is such:• If Input1 is ON (or true) - power (logic) completes the circuit from the left rail to the right rail - and Output1 turns ON (or true). • If Input1 is OFF (or false) - then the circuit is not completed and logic does not flow to the right - and Output 1 is OFF (or false).
- #8 Lets Examine these slides together
- #9 Various inputs can be organised together to give a set output. This is usually termed as conditional logic. Consider the diagram shown and lets examine the logic behind it
- #10 Lets connect the circuit to a PLC as shown in the diagram above. Lets consider the implementation of that circuit in a PLC programming interface.
- #11 Can we build this ladder diagram....Demonstrate the normally closed contact
- #15 Lets take time to understand these exercises.
- #20 For example, when a start push button is pressed, the pneumatic cylinder shown in extends, remains extended for 5 seconds and then returns. Draw the PLC wiring diagram and the appropriate ladder logic.
- #21 Two counters can be combined to make a pulse generator. This is best illustrated by an example.
- #22 When the Start button in Fig 2.24 is pressed the cylinder in Fig 2.23 oscillates,extending for 2 s and returning for 1 s until the Stop button is pressed.