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Counters in PLC Types of PLC Counter

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Counters in PLC | Types of PLC Counter   Counters count rung transitions.   The CTU runs the accumulated value of the counter up on the false to true rung transition, and the CTD instruction runs the accumulated value down.   The CTU and CTD can be used in conjunction with each other. Counters consist of the following components: ACC Accumulated Value PRE Preset Value CD Count Down Bit CU Count Up bit OV Overflow Bit UN Underflow bit By default, data file C5 stores counters, however, other counter files can be added as well. Below is how the C5 Data file would appear: For the CTU instruction:   The CU bit is high when the CTU instruction is true.   The ACC value increments by the value of 1 each time the CU bit goes high.   When the ACC   reaches the PRE, the DN bit will be set.   The CTU will continue to increment the   accumulated value until it reaches the maximum possible value for a 16 bit signed integer   (32767).   If the ...

porcelain insulator in series

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Scaling Analog Input using SCL Instruction in PLC Scale Data

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Scaling Analog Input using SCL Instruction in PLC [Scale Data] Use with processors SLC 5/02SLC 5/03SLC 5/04SLC 5/05 All MicroLogix Example Description Use this instruction to scale data from your analog module and bring it into the limits prescribed by the process variable or another analog module. For example, use SCL to convert a 4-20 mA input signal to a PID process variable. Or use SCL to scale an analog input to control an analog output. When rung conditions are true, this instruction multiplies the source by a specified rate.The rounded result is added to an offset value and placed in the destination. You can use indexed or indirect addresses for the source or destination parameters. Equations used in calculating a linear relationship: Scaled value = (input value x rate) + offset Rate = (scaled max. - scaled min.) / (input max. - input min.) Offset = scaled minimum - (input minimum x rate)   Entering Parameters Values must be between -32768 and +32767 for the following para...

Capacitor and Resistor in One Switch Box

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It would be nice and comfortable doing our work and what we needed are readily available to save time and effort. It lessens the hassle of looking for missing pieces or even using multiple devices to check the accuracy and effectiveness of the equipments we are using. Just like this switch box that has a capacitor and resistor in one unit. It will be easier and faster to check the capacitance and resistance by switching the knobs. This device may look old-fashioned but can really come very handy. This is simple and not that expensive to make and very useful in electronic projects or for the purpose of collecting devices for future use.

Compressor Used in Diesel Locomotives

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The main function of compressor in diesel as well as in electric locomotive is to maintain air pressure in air cylinder. The air is then utilised to blow horn, apply pressure to the moving wheels to stop locomotive, to operate forward and reverse coil to change the direction of movement.