LADSIM - Ladder Logic Editor and Programmable Logic Controller Simulator

Bytronic has introduced a new Windows-based training package, LADSIM, that converts your existing PC into a virtual PLC.

With many different PLC manufacturers in the marketplace, choosing a PLC to teach programming techniques can be a difficult decision. Even if you choose a particular brand, the cost of equipping your laboratory with that PLC and its associated programming software is very often above the available budget. Being software-based, LADSIM is available in a multi-user format that cuts the cost of setting-up multiple stations in your lab, thus bypassing those budgetary problems.

LADSIM is a fully-functional Ladder Logic Editor and PLC Simulator that incorporates all the basic functions used in PLC Programming. With Inputs, Outputs, Timers, Counters, Flags and Shift Registers available, you can develop ladder programs quickly and easily. Each function is simply 'dragged' onto the ladder rung with name tags assigned via a pop-up window. Extra rungs can be added with the click of a button, together with branches to form more complex programs.

LADSIM incorporates seven 'real' process simulations that will test your understanding of Ladder Logic Programming. For each simulation you must develop the necessary ladder code to effect safe control of the scenario. The simulations provided within LADSIM are a Traffic Light, Annunciator, Car Park, Lift, Drinks Machine, Packing Line and Bottling Plant. While LADSIM can be used as a stand-alone teaching aid with its library of internal simulations, it also has the added benefit of being capable of controlling external applications via one of our PC Internal Interface cards.

The LADSIM Editing Screen

The main screen of LADSIM is where the main ladder program is created.

  1. The Ladder Logic Diagram Window. This is where the ladder code is displayed. Each time you add or edit a rung, the result will be shown here.
  2. The Controls box. This contains the ladder symbols that are used to create the ladder diagram. See below for further details.
  3. The toolbar. This includes the standard buttons of LADSIM and allows you to start a new diagram, open an existing file, print, save and comment your ladder diagram.

The LADSIM Controls

Ladder logic programs are made up of symbols that represent the various inputs and outputs of the plant equipment we wish to control. LADSIM uses the same symbols to produce the ladder code on screen and each one is defined below :

LADSIM features a total 12 inputs, 12 outputs, 6 timers, 6 counters, 16 flags, 4 shift registers and 12 reset functions for the timers and counters.

Creating a Ladder Diagram

A ladder diagram can be quickly generated by 'dragging' the required controls from the control panel and dropping them on the rung. In LADSIM, once you have dropped a control onto a rung, a box appears where you can enter information about that control.

For example, if you drop a Normally Open Contact onto a rung, the following box will appear that allows you to input your control references. You can easily change these references by double-clicking on the control.

As your program evolves, you will need to add more rungs and further controls, all of which are just a simple click with LADSIM.

Testing your Diagrams

Once you have created a piece of ladder code it is important to ensure its correct operation before applying it to a real control problem. LADSIM has a unique testing facility built into the package so you can test and debug the ladder programs created in LADSIM.

The Debugging Simulator is activated by clicking on the simulate button or the debugger from the simulate menu. LADSIM's debugging simulator gives you access to the various inputs used in your program. Here you are able to force the inputs simply by clicking on the button and examining the result. All the information provided will help with the debugging and testing of your ladder diagram within a safe environment.

Commenting your Diagram

Documentation of any program is very important that is why LADSIM has both a rung and control commenting feature built-in. A series of text boxes can be displayed beneath each rung of your ladder diagram so you can type in your comments, detailing exactly what task each rung is performing. You have the option to keep the comments in or out of view simply by clicking on the relevant button. Therefore, you can print the ladder diagram with and without comments.

The LADSIM Internal Simulations

Obviously, producing ladder code and using the debugger to test that code is a good start to understanding ladder logic programming. However, it can soon become tedious. Therefore we have created a series of 'real' graphical simulations within LADSIM that you can apply your ladder code to and see how well you can control them. Each simulation is designed to test your ability to write ladder code using the various controls in LADSIM. These simulations are :

Traffic Light

Code must be written to control the sequence of operation of the lights. A typical sequence could be : RED 'ON' immediately After 5 seconds RED and AMBER 'ON' After 5 seconds GREEN 'ON' only After 5 seconds AMBER 'ON' only After 5 seconds Restart Sequence The task would be to code this sequence in ladder logic and operate the lights accordingly.


The Annunciator

In industry, plant conditions need to be monitored and, if there are problems, a way of indicating these problems. An indicator system of this type is called an annunciator. A typical alarm system uses the following sequence to indicate a plant alarm condition to an operator. System healthy - no indication. System in alarm - a flashing light and audible alarm.

The annunciator in LADSIM must be programmed to allow the correct operation.

The Car Park

The diagram shows the layout of a simple car park. It has an entry barrier and an exit barrier. The car park itself has six spaces and a series of displays to indicate whether it is full, has spaces or is empty, with a numerical indicator to determine the exact amount.

Ladder code needs to be written that will allow cars into the car park when it is empty or has spaces and to exit the car park through the correct barrier. Ladder code must also be written to control the display boxes in the centre of the screen.

The Bottling Plant

The graphic is an overview of a simplified bottling plant with a filling station and packing area.

Bottles are fed along the first conveyor, conveyor 1, into the filling station. The bottles must be stopped and filled with milk and then have a cap placed on them. Once accomplished, they go onto conveyor 2 where the cap is screwed on tight. They are finally stacked in the stacker area where they are pushed onto conveyor 3.



The Packing Line

The packing line carries boxes of different sizes which need to be separated into their relevant sizes.

Which direction the boxes go is decided by using the input sensors IP0 and IP1. If a box is short, only one of the inputs is energised at any one time. If it is a long box, then both inputs will be energised.

These results can then be used to activate the correct solenoid and the direction of rotation of the circular plate.


The Lift (Elevator)

A program is required that will drive the lift from one floor to the other on a signal from the call button.

Safety is essential and we must be careful not to have anything obstructing the operation of the doors!



The Drinks Machine

When a coin is placed into the slot, the user should be able to select his or her favourite drink or reject the coin.

It is important to ensure that the coin cannot be rejected once a drink has been selected or that selecting a drink disables all of the other drink buttons.

External Control

In addition to controlling internal simulations, LADSIM can also be used to control real external devices using a Bytronic Interface Card. With a card in place you will then be able to control other Bytronic devices. These devices range from relatively low-cost devices such as the Traffic Control Unit to the more sophisticated devices such as the Industrial Control Trainer or Batch Processing Trainer.

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