Tag: Industrial control
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The General Principle of using a Servo Motor for Position Control
Servo motors are typically employed in closed-loop position control; for example let us consider the following application, where the angular position of the output shaft is intended to follow the reference voltage (ϴref). Figure 1.0 Closed loop angular … Read more
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ZigBee Wireless Protocol for Industrial Communication
ZigBee is an open wireless standard for low-rate networks. It is an IEEE standard 802.15.4 protocol. The physical layer radio operates at 2.4 GHz band carrier frequencies with direct sequence spread spectrum (DSSS). It supports a range of up to … Read more
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What is a Discontinuous Controller?
This is a controller with only 2 switching states, that is, the output signal is switched ON and OFF depending on whether the process variable goes below or above a preset limit or setpoint. An example of a discontinuous controller … Read more
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How Modbus is used in Industrial Networks
Modbus is an open standardized communication protocol that was founded by Modicon. Initially it was designed for the communication among PLCs in industrial applications but it also gained significance use in building automation domain for instance in HVAC systems, DDCs … Read more
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Analog vs. Digital Controllers
Analog signals pass continuously through a full range of values for example a measuring device converts the process variable (PV), say temperature, into a signal corresponding to this temperature. Each temperature value corresponds to a value of the electrical signal. … Read more
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Position Control System using a Microprocessor-Based Controller
Consider the following figure illustrating a position control system employing a microprocessor-based controller with parallel ports: Figure 1.0 Microprocessor-based controller with parallel ports The system above has one output port and three input ports (each port has its own address). … Read more
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Steam-heated Reboiler Control System
When steam-heated reboilers are used in distillation columns and the heating medium is steam, a flow control loop for the steam will typically be incorporated. The control valve can then be placed either in the steam or condensate line. Steam … Read more
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Basic Features of Sercos Automation Bus
Sercos is a short form for serial real-time communication system; a digital automation bus that interconnects motion controls, drives, I/O, sensors, and auxiliary devices such as cameras and weighing stations. Sercos is an open controller-to-intelligent digital device … Read more
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How cycloconverter is used as a direct frequency converter
The cycloconverter provides direct ac to ac transformation with control over both the output voltage magnitude and output frequency. It employs phase-angle-controlled bridges to synthesize voltages. The most common form is the three-phase to three-phase converter illustrated below: … Read more