There are 2 sources for training systems, commercially available system and proposed by education.
Commercially available system
The training systems of commercially available portable fall generally into two categories:
• Hard wired kits.
• Simulators.
Hard wired kits
Generally a kit consists of a PLC incorporating banks of switches to simulate input devices and lamps to simulate output devices. They do not facilitate interfacing industrial of electrical components to the PLC. They are only useful for teaching programming, for experienced programmers to explore new programming students, provide the experience of selecting and connecting actual components to the PLC and generating the input and output (I/O) List to document those connections. The I/O list is a vital part of the documentation required for effective program maintenance and design.
Simulators
Simulators may be sub-divided further in to two categories:
First, PC based using an actual PLC. Generally, simulators have a range of industrial processes (virtual machines) such as “pick and place” and “tank level control systems”. The programmer selects a “virtual machine” from a menu, then writes the program to control it and downloads it to the PLC. The simulator’s PC based serially communicates with the PLC simulating the virtual machines.
Second type the PLC and the process or machines are both virtual, that is no physical PLC exists. Again, as with the previous system the programmer selects a virtual machine from a menu, writes the control program on the PC based virtual PLC. The virtual machine is controlled by the virtual PLC.
Simulators can be used effectively for general engineering training. PLC training with the hard wired kits the simulators are best exploited by students who have the applied skills required to interface the PLC to peripheral devices, have some programming skills and want t develop their programming skills. The simulators in common with hard wired kits do not provide the practical experience of wiring up the PLC.