8051 Can't Be Ignored

Despite it’s relatively old age, the 8051 is one of the most popular microcontrollers in use today. Many derivative microcontrollers have since been developed that are based on compatible with the 8051. A microcontroller   can be defined as computer-on-a-chip built for dealing with specific tasks or a single task, such as displaying or receiving information through LEDs or remote controlled devices. The most commonly used set of microcontrollers belong to 8051 Family. 8051 introduced by Intel in late 1970s. 8051 Microcontrollers are preferred choice for a most of the community of hobbyists and professionals. Through 8051, the world became witness to the most revolutionary set of microcontrollers. Thus, the ability to program an 8051 is an important skill for anyone who plans to develop products that will take advantage of microcontrollers.

PIC is a family of modified Harvard architecture microcontrollers made by Microchip Technology, derived from the PIC1650 originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to “Peripheral Interface Controller”. PICs are popular with both industrial developers and hobbyists similarly to 8051, due to their low cost, wide availability, more dependent on user, extensive collection of application notes, availability of free development tools, and serial programming and also it can be re-programming with flash memory capability. They are also commonly used in educational programming as they often come with the easy to use 'pic logicator' software.

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Programmable Logic Controller (PLC)

     A PROGRAMMABLE LOGIC CONTROLLER (PLC) is an industrial computer control system that continuously monitors the state of input devices and makes decisions based upon a custom program, to control the state of devices connected as outputs.

        Almost any production line, machine function or process can be automated using a PLC. The speed and accuracy of the operation can be greatly enhanced using this type of control system. But the biggest benefit in using a PLC is the ability to change and replicate the operation or process while collecting and communicating vital information.

 

         A PLC is an example of a hard real time system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result.

A PLC consists of following main parts:

What is a PLC input/output?

INPUT	OUT
Sensing Devices	Valves
Switches and Push buttons	Solenoids
Proximity Sensors	Motor
Limit Switches	Actuators
Pressure Switches	Pumps

 

 PLC Operations consist of four steps

            1. Input Scan: Scans the state of the Inputs
            2. Program Scan: Executes the program logic
            3. Output Scan: Energize/DE-energize the outputs
            4. Housekeeping

               

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Displacement Sensors

               These Sensors can be used  to measure the position or change of position of Object. A wide variety of models is available, including Laser Sensors, LED Sensors, Ultrasonic Sensors, Contact Sensors, Eddy Current Sensors, and more.

 A wide variety of models is available,           
                 Including optical sensors, Laser Sensors, LED Sensors, Ultrasonic Sensors, Contact Sensors, Eddy Current Sensors and more.

OPTICAL displacement SENSORS

Principle of measurement of the optical displacement sensor
 

               Light from the light source is condensed by the lens and directed onto the object.Light reflected from the object is condensed onto a one-dimensional position sensing device (PSD)* by the receiving lens. If the position of the object changes, the image formation positions on the PSD will differ, and if the balance of the two PSD outputs changes, the image formation positions on the PSD will differ and the balance of the two PSD outputs changes.
If the two outputs are A and B, calculate A/(A + B) and use appropriate values for the span coefficient "k" and the offset "C".

              The value measured is not the illuminance (brightness), but the two output displacements A and B, and thus even if the received light intensity changes because the distance to the object changes, the result is not affected and linear output proportional to the distance difference and position shift is obtained.

Optical system of the Displacement Sensor

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