Exactly what is it that makes a transmitter smart? (Actually, this term can apply to a lot of instrumentation beyond just transmitters).
There are a few important qualifying characteristics.
• High accuracy
• High reliability
• Use of digital technology
• Remote digital communications availability
The first two points are largely the result of careful design and the use of what’s identified in the third item, digital technology.
There are 5 basic components of a smart transmitter.
-
Analog to digital signal processing is by far the most important aspect of the design when it comes down to the overall performance of the device. Converting that real world analog value, whether it is pressure, temperature, etc. to a digital value has to be done right.
-
CPU considerations are nominal. For field instruments, power consumption is vital. A number of low power devices can fill the bill as the task does not require a large amount of computational ability.
-
I/O (remote communications) allows the instruments to communicate bi-directionally as opposed to the one way analog transmission model for analog instrumentation.
-
ROM and RAM contain both the operational program of the device (firmware) and the scratch memory needed for any assigned task.
-
Digital to analog signal generation provides backwards compatibility with existing systems and faster updates than may be available through digital communications.
Download Full Article:
Calibration of Smart Instruments.pdf (293.8 KB)