Automation in industries is the need of the hour. Everything is done electrically and not manually, right from a really unnoticed process like moving the conveyors to something as power intensive as running pumps. Industrial automation is primarily necessary for high end production and also product quality controls. Mainly, in industries, such automations are carried out by intelligent systems called Programmable Logic Controllers with the help of a host computer. A PLC, is in an actual sense, an electrical version of a microcontroller unit. It’s more generic and also controls high power tools which generally work at really high voltages, unlike the microcontroller that merely works at considerably small voltage values. Basically, it intelligently controls whatever is programmed onto it by the host computer. This controller, being so versatile, is highly expensive, due to it’s high rising demand and also it’s operability credits. A PLC generally has a set of input and output ports to with the external peripherals are connected, which are to be electrically controlled by the PLC. Looking into the flow of working of the PLC, the processor tries to make decisions in accordance to the program, generally written by the user using some logic used to program these units. Some of these logics include Function Block Diagram, Ladder Diagram, Structured Text, Sequential Function Chart and Instruction List.
The objective is to create an Open Source PLC, which has the capabilities of the industrial PLC, but the catch here is, it’s much cheaper and simpler to work with. It incorporates a development board, that works on AVR’s ATmega16A IC, giving upto 40 pins, most of which can be used and programmed as the Input-Output pins as it’s done on a PLC. Moreover, the logic used here is Ladder Logic which is one of the easiest and also, robust in terms of its efficiency. Main point here is, this device is a standalone device, which can work without the host system being there, just being powered by a source. HEX files to be generated according to the controller are generated by a software called LDMicro, freely available for Windows and Linux users alike. The programming on the board is done via a RS-232 cable by serial communication. All the processor wants now is a code to be dumped on it to start automating your small needs.
This prototype will be helpful for students to get the feel of working with the PLCs, to control small automated systems. It’ll also be easy as there’s no coding involved and it’s using a GUI that is user friendly and also efficient. Along with the development board, which can be used as microcontroller also, there are various hardware modules to start off with and later the students can cone up with their own hardware setups and test their modules, with the board. It’s really versatile as it can suit your microcontroller needs and also work as a PLC. All you need is the HEX code for your desired usage with hardware.
The manual covers the basics of using the associated software and also explains the interfacing with the hardware. Certain simple experiments are given so as to get accustomed to the software usage. Later, some modules that can be made using the various sensors discussed in the preceding sections are covered. Then the imagination of the student and the need can drive the making of various other modules according to the students need. The below images represents the Open Source PLC board which includes three different setups connected to it. Where one can write different ladders and run on it. It includes a Traffic light control setup, A rope way conveyer setup, A Heater setup and An Elevator setup.