long term timers

Example 1:
Long-term Timers
The following program examples show two ways to create long-term timers
with standard TIM and CNT instructions.
Two TIM Instructions
In this example, two TIM instructions are combined to make a 30-minute
timer.


TIM and CNT Instructions

In this example, a TIM instruction and a CNT instruction are combined to make a 500-second timer.TIM 0001 generates a pulse every 5 s and CNT 0002 counts these pulses. The set value for this combination is the timer interval × counter SV. In this case, the timer SV would be 5 s x 100 = 500 s. With this combination, thelong-term timer’s PV is actually the PV of a counter, which is maintained through power interruptions.

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Planning your project

Often people say fail to plan, you plan to fail. It is very-very important to plan your work in designing your PLC projects. identify your project requirements, inputs and outputs involve etc.

Today i will give you a free PLC programming on how to do a PLC controller for a water tank system. This is a typical exam question for PLC beginner.

The inputs involve are 1 start button addressed at 0.00 and 2 level switches addressed at 0.01 and 0.02 respectively. The one address at 0.01 will turn ON whenever the tank is empty thus it will switch ON the water valve (output) which is address at 10.00. The other level switch will turn ON whenever the tank is full and consequently will turn the water valve OFF. By doing this control, the water tank will not run empty. The water will fill into the tank whenever the empty switch is ON. Address 14.00 and 14.01 is just internal relay address to sequence the programming.

Click HERE for your ladder logic

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PLC open source, free codes for you

This is your source for PLC programming. Finally, a FREE place to practice your PLC programming skills. The PLC Simulator is here to help you learn PLC programming.
For simple directions please view the help section. The help section can be found on the top menu of the PLC simulator.

Suggestions for improvement are always welcomed. If you would like to share any of the PLC programs you write via the simulator, please upload them to the downloads section of the site. You may also wish to search there for some examples other people have written.

Enjoy the program and remember that your feedback is welcomed as well as your suggestions for improvement. NO requested feature will be considered crazy.