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SEIRI SORT SISIHSEITON STRAIGHTEN SUSUNSEISO SWEEP SAPUSEIKETSU STANDARDIZE SERAGAMSHETSUKE SUSTAIN SENTIASA

programmable controller is a digital computer used for automation of industrial processes

PLC is designed for multiple inputs and output arrangements.These connect the PLC to sensors and actuatorsresistance to vibration and impact

i/p side > can be Digital or analog signalso/p side > PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relaysPLC is an example of a real time system which output results must be produced in response to input conditions invent as replacements to relays, cam timers, and drum sequencerseconomic due to the lower cost

simple ladder logic which appeared similar to electrical schematic diagrams.

Digital or discrete (like Pushbuttons) signals behave as binary switches, yielding simply an On or Off signalDiscrete signals are sent using either voltage or currentFor example, a PLC might use 24 V DC I/O, with values above 22 V DC = On, below 22v= off

Pressure, temperature, flow, and weight are often represented by analog signalsPLCs typically use 16-bit signed binary processors,the integer values are limited between -32,768 and +32,767Analog signals can use voltage or current with a magnitude proportional for the value of the process signal0 - 10 V input would be converted into an integer value of 0 - 32767.

5 programming languages for programmable control systems:1.FBD (Function block diagram),2. LD (Ladder diagram),3. ST (Structured text, similar to the Pascal programming language),4. IL (Instruction list, similar to assembly language)5.SFC (Sequential function chart)

PLC brands are Siemens , Allen-Bradley, ABB, Mitsubishi , Omron, and General Electric .

1.you need to select an instrument or a system that you wish to control2.you need to specify all input and output instruments that will be connected to a PLC controller3.make a ladder diagram for a program by following the sequence of operationsFinally, program is entered into the PLC controller memoryneed to check once again whether all input and outputbringing supply in, system starts working

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ADVANTAGE PLC disadvantages of a classic control panel are:Cost effective for controlling complex systems. - Too much work required in connecting wiresFlexible and can be reapplied to control other systemsquickly and easily.

- Difficulty with changes or replacements

Computational abilities allow more sophisticated control - Difficulty in finding errors; requiring skillful work force

Trouble shooting aids make programming easier andreduce downtime

When a problem occurs, hold-up time is indefinite, usuallylong

Reliable components make these likely to operate for years

before failure