This term was coined by Honeywell, USA in 1985. The first generation of instruments like flow meters were mechanical devices. The next generation used electronics for improving performance. With electronics, adjustment of range, span, zero adjustment etc. could be carried out with potentiometers. (i.e. ease of setting parameters was achieved) In some cases functions like linearization, annunciation (exceeding process limits) etc. were also integrated. With the help of 4-20mA transmitter, data transmission over longer distance was made easy. There was a considerable jump in technology in terms of improved accuracy, response, interface with operator, ease of adjustment of range and span. This was made possible with use of digital circuits, microcontrollers, ADC, DAC. Today we hear about not only Smart Transmitter/Instruments, but Smart Control Valves, Smart Machines like Microwave Ovens, Washing Machines etc. Digital Oscilloscope also can be categorized as Smart Oscilloscope. Most of these are called embedded applications. Todays microcontrollers like PIC [from Microchip] & Atmel consume negligible power, have built in ADC/DAC with multiplexer (multi channel). Also they have in built timers, EPROM, E2PROM, RAM, Watch dog timer on a chip. The operating frequencies are also high. So these are finding applications in every field. (high frequency is not needed in all applications) These processors can work on very low frequency. This is very beneficial, because the power consumption depends on the operating frequency. For many instruments operation frequency of C used may be as low as one kHz for satisfactory operation.
Following are some of the features that can be added in any smart transmitter (or any other equipment)
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| SMART DEVICE |
- Communication with master control, printers and other units
- Linearization - Look up tables - Use of formula
- Compensation of secondary effects like temperature/pressure
- Auto Calibration
- Auto offset adjust
- Auto Range Selection. (DMM)
- Span adjustment
- Remote programming of parameters
- Self-diagnostics
- History memory
- Improved accuracy
- Annunciation
- Sensor characteristics may be stored
- Inter locking with other system easy
- Easy math calculations
- Smart displays
- Use of PID possible
- Password for locking parameter settings
- Code (in memory) can be bared
