In PLC programs, the inputs are read in each cycle and logically linked with the logic of the program. The result is then written to the outputs. This happens in every cycle and thus a defined sequence can be programmed via the PLC.
There are two types of programs: logic control and sequence control.
In logic control, inputs are written directly and logically to the outputs. The combinational logic results in an output or a logical variable.
With sequence controls, states and state transitions are defined. Thus, inputs are logically evaluated on the outputs depending on the state. One advantage of sequence controls is that defined states and state transitions are available.
The program must now program the sequence of states and the state transitions. However, he must also anticipate and program the non-permitted states and the non-permitted state transitions. Thus, a program is created for a sequence, states, prohibited states and state transitions.
Thus, in each state, all inputs must be checked to see if the input image is permitted and matches the state. If the input image matches the step-on condition, the state changes to the next state. The outputs are switched with the step-on and movements or signal changes are reflected in the input image. In this way, all actions are executed with a defined input image.
The sequence is basically determined by the process. Mechanics and electrics define the assemblies with signals and actuators from the specifications, which are mapped in the design by a circuit diagram.
The program must then transfer this information about the sequence with the inputs and outputs into a program. This is a manual process and it basically depends on the program how good the software quality is.
The process parameters that are important for the application are defined later via the requirements of the HMI. These must then be related to the process.
Mechanical, electrical engineering and software usually work independently of each other and with little coordination until commissioning. The planned components come together during commissioning. And it is not uncommon for the first complications to arise there. Thus, commissioning and implementation are delayed. In most cases, the problem has to be solved via the software.
With Selmo, a requirements analysis is carried out right at the beginning and mapped in the form of a model. The requirements for the mechanical and electrical systems are derived from this model. The requirements for the software, which describe the logic of the process, are generated directly into an executable PLC program. For the software, it is only a matter of programming the non-existent functions such as drivers and interfaces from the mechanical components. Thanks to the common model for all experts, the functions and implementations come together ideally at the time of commissioning. Since Selmo carries out the programming completely automatically, the structure and the logical sequences are 100% coordinated with the model requirements.
The software that the mechanics and electrics need to operate a machine is automatically generated by a novel algorithm. The software is particularly characterised by the fact that it monitors all signals and states at all times. In order to generate such equally high quality software, an inhuman amount of programming would have to be done.
Selmo monitors all inputs in every state and reacts to every deviation. In this way, the model is constantly compared with the real machine. In the event of deviations, the software reacts with a fault and outputs detailed information about the cause of the fault. In individual programming, it takes a great deal of effort to develop a program that completely describes a complicated system such as a plant.
Selmo automatically generates a program that completely describes a complex system such as a plant.
Selmo solves the complexity problem in PLC programming with the aid of automatic intelligence.