Intelligent transmitters

Intelligent transmitters have two major components (1) a sensor module which comprises the process connections and sensor assembly, and (2) a two-compartment electronics housing with a terminal block and an electronics module that contains signal conditioning circuits and a microprocessor. Figure 6.9 illustrates how the primary output signal is compensated for errors caused in pressure-sensor temperature. An internal sensor measures the temperature of the pressure sensor. This measurement is fed into the microprocessor where the primary measurement signal is appropriately corrected. This temperature measurement is also transmitted to receivers over the communications network. 

Insulation see also lagging 554 Intelligent transmitters 240,241,242 Intensity of turbulence 701 Interface evaporation 484 Interfacial turbulence 618 Internal energy 27,44... 

Intelligent transmitters can automatically convert level readings into volume. 

Most pressure sensors detect the difference between the measured value and a reference. In the case of absolute pressure sensors, the reference chamber cannot be evacuated to absolute zero, because it can only be approached within a few thousands of a millimeter of mercury (torr). In the case of positive pressure detectors, when the barometric pressure is the reference, atmospheric pressure variations can cause errors up to 25 mmHg. Intelligent transmitters can also operate with multiple references and switch them as required. 

Differential pressure-type detectors have already been discussed in connection with both flow (Section 3.9.9) and level (Section 3.11.2) measurements. Therefore, only their ranges and accuracies will be briefly mentioned here. The basic error of d/p transmitters ranges from 0.1 to 0.5% of the actual span. Added to this are the errors caused by the temperature and pressure effects on the span and zero of the instrument. For intelligent transmitters, the pressure and temperature corrections are automatic, and the overall error is 0.1 to 0.2% of span. 

Intelligent Transmitter 4-20 mA or As above but also unpredictable due to programmable electronics. 

Figure 6.11. Intelligent differential-pressure cell with transmitter...

Tracking surveillance technology is varied in design and form. It ranges from simple beepers to sophisticated intelligent transportation systems. For example, there is radar to monitor over the horizon bi-static sensors for passive retrieval of emissions (cellular phones) or active sonar-hke capacity tagging systems that use projectiles to attach transmitters to moving objects illumination telescopic and detection systems. 

Smart Transmitters and Associated Protocols—Intelligent Hardware... 

An instrument which not only measures a variable, but also carries out further processing in order to refine the data obtained before presentation either to an observer or to some other stage of the system, is generally termed intelligent or smart. In practice, additional functions are usually available as well as the data-processing facility and these are all normally contained within the transmitter of the measuring device. These so-called smart transmitters are microprocessor-based and enable the device ... 

The cost of an intelligent instrument can be twice that of the equivalent device without the smart facility (the latter is termed a dumb instrument)(99). However, the use of a smart transmitter does generally improve the inherent accuracy of the sensor itself. 

The size of orifice-type flow sensors is limited only by the pipe size they are installed in, and their pressure and temperature ratings depend only on the limitations of the d/p detector used. Their measurement error is the combined orifice and d/p readout error, which in a standard installation over a 3 1 range is about 2% FS, and with an intelligent and multirange transmitter it can be reduced to 1% AF over a 10 1 range. 

The array of intelligent temperature transmitters on the market seems almost endless. Some common features of the leading models are universal... 

Another type of monitor is a field mounted hazardous or toxic gas detection device. Such permanent gas detection systems (see Figure 11-7) protects personnel and equipment finm virtually any toxic or combustible gases through audible and visual alarms in the field and/ or on a control board. Permanent gas detection systems consist of a combination of transmitters, intelligent sensors, controllers, and accessories. These types of monitors are used to ... 

Distributive controi systems combine some of the most innovative technologies into an interactive network of intelligent microprocessors, application software, and communication networks. The hardware for a DCS includes a host CPU or programmable logic controller (PLC), intelligent field devices (transmitters, controllers, and control valves), remote CPU, and keyboard. This type of system offers the highest level of operator interaction. 

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