Introduction

TrySim is a development system for PLC programs that allows not only to simulate a PLC, but also to reproduce the run of the machine, which has to be controlled. Therefore any program created by TrySim can be tested and optimized under real conditions by using a PC and Win’98/NT/2000/XP/VISTA only.

Optional external PLC simulations or real steerings can be connected. In TrySim only the machine will be simulated.

For the professional programmer this means a considerable simplification and acceleration for the commission of a system and provides various options for the beginner to create different types of machines by writing and testing corresponding programs and without being dependent upon the workstation at his/her training center.

In preparation for a simulation of the machine, you can choose among a variety of elements, such as motors, cylinders, limit switches, light barriers etc. These elements can be arranged in a three-dimensional manner, the graphical representation corresponds to a technical diagram. In designing TrySim high priority was assigned to clarity and speed of execution but not to optical effects which do not provide any benefit. The machine can also be displayed in a three dimensional view.

The simulated PLC utilizes the instruction set of Siemens S7-400. Our program editor has little resemblance to the STEP®7 development system, because it is not our intention to replace the training at an original Siemens programming device.

If you want to run the completed program on a real PLC, you can easily transfer it to the STEP®7 system. The inverse direction, to write a program on a Siemens STEP®7 system and transfer it to TrySim, is also possible without any difficulties.

STEP®7 and S7-400 are registered trademarks of Siemens AG.

History of TrySim

TrySim has been fully developed within our company. Our job is to develop controls for special devices, such as transport installations. Although these are rather simple machines, anyone who has ever tried to control a system of 30 segments of different switches, turntables, an oven, and a scale, will confirm that many things may go wrong. Moreover, the customer asks for answers to questions as follows:

How many paletts (the exact number) will pass the machine per hour?

Will a jam caused by a 10-minutes break be disentangled to be resolved in a reasonable time intervall or will it require a substitute?

Answering questions such as these requires a considerable amount of theoretical calculations and a significant amount of time. Moreover these machines are normally mounted completely at the site of the customer and it is not before the last screw has been tightened that the real program testing can begin. Regarding this test, the programmer uses a development system which can easily increase to an amount of several million Euro. So everything must be done to shorten the duration of this final test.

Our purpose was to shorten the very expensive commissioning time and therefore we have developed TrySim, with its machine and PLC simulation, and have used it successfully. We have also found that the procedure of writing the program on the original development system first and then transfering it to the simulation program has turned out to be unsatisfactory. This is why we have also integrated program editors into the simulation system.

Of course, there is not only a need to simulate transport installations. As a result of a continuously growing range of elements (which is still expanding) the types of machines that can be simulated has been expanded, even if, at this stage, the simulation is essentially confined to mechanical machines and gadgets.

Basic considerations

For a simulation to be useful it has to fulfill the following requirements:

1. Creating and generating the simulation has to be easy and speedy. It is of no use saving 10 hours of commissioning time, but loosing 100 hours spent on creating the simulation.

2. It has to be realistic as far as the PLC is concerned. If, e.g., a output/motor has been set, it must be followed by an event of the corresponding limit switch at the correct time. There is no need to look realistic, as such a demand would be in contradiction to the first requirement.

3. It has to be flexible because of the immense variety of elements within mechanical engineering.

4. It requires efficient real time calculations, i.e., it must at least match the speed of the real machine, and as far as possible, should be obtainable even a higher speed.