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PROFIBUS

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 PROFIBUS PROFIBUS or Process Field Bus was introduced in 1989 and it is sometimes confused with PROFINET. It links plant automation modules with the process control. PROFIBUS uses a multi drop single cable to connect the devices. This method is cost effective especially for larger sites when compared to old methods. Its installation cost is low and it is easy to find faults as well because it is a single cable. Types of PROFIBUS There are two types or versions of PROFIBUS commonly known as 1.    PROFIBUS DP 2.    PROFIBUS PA Here is a brief introduction to both of these types. PROFIBUS DP It runs over two core screened cable that is violet sheathed and its speed varies from 9.6Kbps to 12Mbps. A particular speed can be chosen for a network to give enough time for communication with all the devices present in the network. If systems change slowly then lower communication speed is suitable and if the systems change quickly then effective ...
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Introduction: PID Controller Design

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Introduction: PID Controller Design In this tutorial we will introduce a simple yet versatile feedback compensator structure, the Proportional-Integral-Derivative (PID) controller. We will discuss the effect of each of the pid parameters on the closed-loop dynamics and demonstrate how to use a PID controller to improve the system performance. Key MATLAB commands used in this tutorial are:  tf  ,  step  ,  pid  ,  feedback  ,  pidtool  ,  pidtune In this tutorial, we will consider the following unity feedback system: The output of a PID controller, equal to the control input to the plant, in the time-domain is as follows: (1) First, let's take a look at how the PID controller works in a closed-loop system using the schematic shown above. The variable ( ) represents the tracking error, the difference between the desired input value ( ) and the actual output ( ). This error signal ( ) will be sent to the PID controlle...
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Introduction : Ultrasonic Flow Measurement

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An ultrasonic flow meter is a type of flow meter that measures the velocity of a liquid or gas (fluid) by using the principle of ultrasound. Using ultrasonic transducers, the flow meter can measure the average velocity along the path of an emitted beam of ultrasound, by averaging the difference in measured transit time between the pulses of ultrasound propagating into and against the direction of the flow. Ultrasonic flow meters are affected by the temperature, density and viscosity of the flowing medium. They are inexpensive to use and maintain because they do not use moving parts, unlike mechanical flow meters. There are three different types of ultrasonic flow meters. Transmission (or contrapropagating transit-time) flow meters can be distinguished into in-line (intrusive, wetted) and clamp-on (non-intrusive) varieties. Ultrasonic flow meters that use the Doppler shift are called Reflection or Doppler flow meters. The third type is the Open-Channel flow meter. The basi...
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