Tag: instrumentation
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Basic Features of Controller Area Network (CAN)
Controller Area Network (CAN) is a serial communication protocol developed primarily for applications in the automotive industry. It is also capable of offering good performance in other time-critical industrial applications. The CAN protocol is optimized for short messages and uses a carrier sense multiple access (CSMA)/Arbitration message priority (AMP) medium access control technique. Therefore CAN…
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Technical Aspects of Foundation Fieldbus
Foundation fieldbus (FF) is an all-digital, serial, two-way communication system for industrial applications. Foundation fieldbus specifications include two different configurations: H1 and HSE. H1 Foundation Fieldbus (FF) H1 FF communication system is mainly applied to distributed continuous process control; running at 31.25 kbps. It connects digital field equipment such as sensors, actuators and inputs/outputs allowing…
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Topological Network Structures used in Fieldbus Systems
Topology is an important property of fieldbus. It is employed in the selection and definition of the best and suitable physical layout of the fieldbus network. The physical layer of the fieldbus has to meet somewhat demanding requirements like immunity to electromagnetic disturbances, robustness, intrinsic safety for hazardous areas, etc. The most important topologies for…
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What is Fieldbus in Industrial Communication Networks?
Fieldbus can be defined as a digital, serial, multidrop, data bus for communication with industrial control and instrumentation devices such as sensors, transducers/transmitters, actuators, local controllers, etc. Alternatively, Fieldbus can be defined as a digital, two-way, multidrop communication link among intelligent or smart measurement and control devices. It serves as a local area network (LAN)…
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The Conditioning of Thermocouple Sensor Voltages
Consider the circuit below: From the figure above, the sensing junction and reference junction are connected in series. When the junctions are at the same temperature the voltage output from the junctions is zero and the output from the amplifier is zero. When the junctions are at different temperatures, there is a differential voltage at…
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Features of HART Communication Protocol
HART is an acronym for (High Addressable Remote Transducer). HART is implemented in two ways in industrial instrumentation networks: Point to point system Multidrop system HART Point to Point System Here serial communication data is superimposed onto a standard 4-20 mA loop signal as shown in figure 1(a): Frequency shift keying (FSK) is used with…
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RTD 2, 3, 4 Wire Sensor Connections
The resistance temperature devices (RTD) can be connected directly to the controller peripheral amplifiers using 2-wire, 3-wire or 4-wire lead configuration. The wires in all these connections are in shielded cables. The RTD is usually driven from a constant current source (I) and the voltage drop (V) across the RTD is measured. RTD 2-wire connection…
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How to Connect a DP (Differential Pressure) Flow Sensor to a DP Transmitter
The DP Transmitter should be mounted with a manifold block as illustrated in the figure 1(a) below to allow for maintenance. Valves B and C are the isolation valves while valve A is an equalizing valve. Valve A is used along with valves B and C to zero the transmitter. In normal operation valve A…
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Instrumentation Sensors and Transducers – Multiple Choice Questions & Answers (MCQ4)
The Answers have been provided at the end of the Questions: Q1. Which of the following sensors is used to measure displacement? A. Thermistor B. LVDT C. Dall tube D. None of the above Q2. Which of the below listed sensors is used for temperature measurement? A. Strain gauge B. Thermistor C. Piezoelectric crystal D.…
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How Signal Processing Circuits are protected from high currents & voltages
Protection against high currents and voltages is a very important requirement for signal processing circuits. A high current can be protected against by the incorporation in the input line of a series resistor to limit the amount of current flowing to an acceptable level and a fuse to break if the current exceeds a safe…