What Are the Advantages and Disadvantages of PLCs Over Micro

Discussion 1) What are the advantages and disadvantages of PLCs over micro-controllers? Before discussing about the advantages and disadvantages of PLCs over microcontrollers we need to clearly identify what they are. A microcontroller is a little computer. Microcontrollers are dedicated to do one task and run one specific program. The program is stored in ROM (read-only memory) and generally does not change. Microcontrollers are often low-power devices. A microcontroller has a dedicated input device. A PLC can be identified as a special microcontroller with extra peripherals and protection circuits designed for industrial applications. Now let’s discuss the advantages and disadvantages of PLCs over micro-controllers. Advantages 

Scalability: Microcontrollers are too small to handle large amounts of I/O s where

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PLCs can do so. Modularity: Almost all PLCs are modular. I/O s and other modules can be easily

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added to and removed in PLCs. PLCs are made for rugged and tough to suit industrial environment. A microcontroller cannot withstand dust like there is in cement industry, for example. A microcontroller cannot work in environments with high levels of

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humidity, corrosion, vibrations, etc. Most of the PLCs can be easily integrated with other industrial networks by adding just another communication module. It is optimized to handle several

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digital inputs and outputs. This is not the case with microcontrollers. PLCs are reliable, less complex, easy to programme. PLCs have protection mechanisms while microcontrollers don’t.

Disadvantages 

For Small Machines using microcontrollers is better and cheaper while PLC is costly.  PLC is basically for Industrial use for controlling machinery, while microcontrollers can be used for any types of application. 2) List down various kind of PLCs available in the market. Unitary PLC A unitary PLC is the simpler type of controller, and contains all of the basic system components within a single housing, or box. These components typically

include the processor, which runs the software program, in addition to ports for input and output connections. Unitary PLCs are typically attached directly to the device or application that is being controlled. Modular PLC A modular PLC contains several different modules that can be coupled together to build a customized controller. Typically, a base module contains core functions such as electrical power regulation, the computer processor, and input connections. Additional modules, including analog to digital signal converters or additional outputs, can be added to this core unit as needed. This modular design allows a PLC to be customized and changed easily. Rack Mounting PLC The rack mounting type of PLC is similar to the modular concept, but is implemented differently. Whereas each module in a modular PLC connects to the base unit directly, a rack mounting PLC keeps each module separate. All extra modules are connected through a network, and modules are held in organized racks. This approach allows for larger systems to be built without becoming overly cluttered and complicated. Modules are well organized on the rack and can be removed and reinserted as needed. Below given is a list of PLC manufacturers.          

ABB Allen Bradley Alstom Bosch Delta Devolo Echelon General Electric Hitachi Honeywell

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Mitsubishi Modicon Motorola Omron ON Semiconductor Panasonic Qualcomm Atheros Schneider Electric SiConnect Siemens

 3) Discuss the problems encountered in conducting the experiment and how you overcome it. Also state the reasons for the problems that encountered   A problem occurred while we were trying to blink a bulb using PWM control. We tried to give the output of the PWM to a bulb using an output in the software package. But we could not get the desired output. Only later we found that output was already assigned to one of the bulbs while we were configuring the PWM and there was no need to define the output separately  

again. One of the wires were separated in the variable resistor which was used to change the speed of the DC motor. I got the chance to solder the wire and put a insulator cover to the soldered junction