In this article, we will list some free online PLC Simulator tools. These online ladder logic simulator tools are beneficial for engineering students, as they can practice ladder logic programming without installing any software.
PLC stands for Programmable Logic Controller. It is an important organ of industrial automation. You can consider PLC as an industrial computer that controls all the automation processes in different types of plants, like food manufacturing plants, chemical industries, textile industries, paper mills, sugar mills, etc. In order to automate the production process, automation engineers feed a program into the PLC.
To write a program in PLC, an automation engineer needs to know any of the programming languages that the PLC supports. Some of these programming languages are FBD (Functional Block Diagram), SFC (Sequential Function Chart), LLD (Ladder Logic Diagram), etc. Out of these programming languages, the Ladder Logic Diagram is the easiest programming language.
Best free Online PLC Simulator Tools
We have the following online PLC simulator tools on this list:
- PLC Fiddle
- PLC Simulator Online
Let’s explore the features of these free online ladder logic simulator tools.
1] PLC Fiddle
PLC Fiddle simulator is a free online ladder logic simulator tool. To use this tool, you simply have to visit its official website, which is plcfiddle.com. After visiting the website, you will see a default ladder logic diagram there. The left panel of the website includes the status of I/Os.
PLC Fiddle is a basic PLC simulator that you can use to hone your programming skills. It is a perfect tool for a beginner. In the right panel, you will find some basic programming functions in different tabs. Let’s have a look:
- Contacts: It contains the input coils, including Normally Open contact, Normally Closed contact, and Reset Input coils.
- Output: You can connect output coils on the rung by clicking on this tab.
- Math: As the name implies, it contains the mathematical operators including Add, Subtract, Multiply, and Divide. Apart from this, you will also find the Move operator here.
- Compare: In certain instances, we require to insert a comparator in our PLC programming. For example, if a power plant requires the coolant to turn on if the temperature rises a certain value. You can practice such types of PLC programming problems on the PLC Fiddle simulator website. Different types of comparators are available in the Comparator tab, including less than, greater than, equals to, not equals to, etc.
- Timer and Counter: Here, you will find three types of Timers, namely, On Delay, Off Delay, and Retentive Timer. If we talk about the Counters, Up and Down Counters are available here. In addition, the Reset input is also available here.
- Other: This tab includes some basic functions, like Save a program, Add a Rung, Add a branch to a rung, and Trash a component.
How to use the PLC Fiddle simulator
We are listing here the instructions to use the PLC Fiddle simulator.
1] As we have explained above, when you land on their official website, you will see a default program. So, first, you have to delete all the components of the default program. For this, click on the Other tab. Now, drag each element on the rung and drop it in the Trash box. After that, you have to delete the previously defined inputs and outputs. For this, simply click on the cross button next to the I/Os. Please see the screenshot below:
2] Now, you have to define your own inputs and outputs. For this, click on the box on the left pane and type the name of your input and output. After typing the name of input or output, you can define whether it is Boolean, Number, Timer, or Counter from the drop-down menu. Do note that, PLC Fiddle accepts the time in seconds only. Hence, you have to do some calculations if you want a delay of certain minutes or hours.
When you are done, click on the Add button. To add a rung, go to the Other tab and then click on the Add Rung button.
3] Now, to add elements on a rung, simply drag them from their respective tab and drop them on the rung. After adding all the elements, define their address by selecting the required field from the drop-down menu. When you are done, click on the input switches to change their state, and the PLC Fiddle simulator will show you the real-time simulation of your program.
I have taken an example to turn off the motor after 50 seconds. The PRE shows the time that we have entered, whereas, the ACC displays the time when you run the simulation. Have a look at the ladder logic diagram of this simple problem.
To save your project, first, click on the Other tab and then click on the Save button. When you save your project, the website will display a URL in a popup window. You have to save this URL to access your saved project. For this, copy the URL from the popup window and paste it in the notepad or any other application on your PC, and then save it.
2] PLC Simulator Online
PLC Simulator Online is another free online PLC simulator tool on this list. To use this tool, you have to visit its official website. Like the PLC Fiddle simulator tool, this one also has a sample project. You have to click on the File icon to load the sample project.
How to use PLC Simulator Online
Let’s see the steps to use this free online PLC simulator tool.
1] First, you have to define the I/Os. For this, click on the Add new variable field and enter the name of your I/O. After that define its type, like Boolean, Counter, Timer, etc., from the drop-down menu. When you are done, click on the Submit button.
2] After defining all inputs and outputs, add elements on the rung. For this, first, select the rung on which you want to add the element and then click on the element from the menu. After adding an element, double-click on it and define its address. Follow this procedure to draw your ladder logic diagram. Use the arrow buttons to move the selected element on your ladder diagram. When you are done, click on the green Play button to start the simulation.
Do note that the Timer in PLC Simulator Online accepts time in milliseconds. This means if you want a delay of 5 seconds, you have to enter the value 5000. Do your calculations accordingly for the delays of minutes and hours. The below screenshot displays an example of ladder logic in which Motor 1 will be turned on with Switch 1 and Motor 2 will be turned on 20 seconds after Motor 1.
The PT shows the time that we have entered, whereas, the ET displays the time when you run the simulation. Unlike the PLC Fiddle Simulator, this freeware does not have a save the project feature.
How do you use a PLC Fiddle Counter?
Let’s see how to use a PLC Fiddle Counter. Let’s understand the PLC Fiddle Counter:
- EN: This indicates the status of the input pulse that the Counter receives. Hence, it will turn on with every rising pulse and turn of with every falling pulse.
- Q: It is the output of the Counter.
- ACC: It indicates the total number of counts.
- PRE: Here, you have to enter the number of counts for your Counter.
Let’s take an example, in which a parking area has a space to keep a maximum of 5 cars. When all the 5 cars are parked in the parking area, its doors are closed automatically. Sensor 1 gives input to Counter 1 for every car entering the parking area. Every rising pulse of Sensor 1 increases the Counter 1 value by 1. When the Counter 1 value reaches 5, it will turn on Relay 1 due to which the NC contact will become NO. This will turn off the Parking Gate.
To reset the counter, you have to enter 0 in ACC.
That’s it. Which online PLC simulator tool is your favorite? You can tell us in the comments below.
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