PC-Sim: Siemens S5 100U PLC simulator
This PLC simulator software is included in the AW-SYS package. It simulates the Siemens PLC model S5 100U.
This window contains an image of the PLC. Obviously, the displayed image changes according to the model being used. The window has been developed to display a unit as similarly shaped as possible to an actual PLC. Passing to an actual PLC, if desired, will then be an easier task. All the windows incorporate digital input and output status LEDs. Just like in an actual PLC, an input LED ON status indicates that the linked contact is closed; an output LED ON status indicates that the corresponding output has been enabled.
16 push buttons/switches are available in the PLC window. They are used for the control of digital inputs when only the PLC is employed (without the simulated equipment) or when PLC inputs are not all connected to the equipment.
These push buttons/switches may either function as push buttons or as switches; the different arrangement indicates the proper function:
where the double arrow and single arrow indicate a toggle (bistable) function or a one-shot (monostable) function, respectively.
The Ladder Diagram is certainly the most widely used programming language for PLC. It is a graphic programming method. An electrical wiring diagram including a sequence of several circuits is constructed between two vertical lines representing the power supply. The PLC carries out each command in sequence when a user program is run.
The PC-Sim ladder editor allows easy editing of the program by combining fast operations performed with the mouse and powerful advanced editor options: e.g. cut, copy, paste.
The diagram is organised using the tools available in the Tool Box and the Popup menus which become available by clicking the mouse right button. A check for syntax accuracy of the operands, which may well be introduced as symbols, is carried out on completion of each type-in operation. When the implemented program is run, the editor itself allows debug information to be displayed. Different colours are used to distinguish and display elements such as closed contacts, energised coils and electrical flow. Colours will be real-time updated according to processing results and variations of field signals.
AWL, also known as STL or Statement List programming language, is one of the most widely used methods for programming a PLC. Writing a program in AWL implies typing-in a set of instructions, each one representing an elementary task that the CPU of the PLC will perform in sequence. Each instruction in typed in one line format; each line includes one instruction only.
In general, an instruction consists of an operation and an operand. The operation specifies the task that the CPU must perform and the operand specifies the object where the task must be performed.
The PC-Sim AWL for PS3 allows easy, fast type-in of instructions and an immediate call of system modules. The syntax is checked immediately, and the programmer is immediately alerted should any error occur. When the implemented program is run, the editor itself allows the debug information to be displayed. Iinformation regarding the main PLC registers and operand status will appear as each line is run. This information will be real-time updated, according to processing results and variations of field signals.
The project block list is displayed in table format, the program editor used for each block and the current status. The window allows for the use of block handling procedures through the Create, Rename, Remove, Edit and Debug commands.
The remaining windows included in the program are common to all PLCs. For a more detailed description see PC-Sim: the PLC simulator.