lsli02.4up

lsli02.4up - 02-1 02-1 Process State, Sensors, and...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 02-1 02-1 Process State, Sensors, and Interfacing Function of sensors: convert physical quantity to information. Information will (usually) be read by computer via an interface. Ultimately, the information, in the desired form, will be stored in a memory location. The following steps are typical: 1: A transducer converts process state to a raw electrical quantity. 2: A conditioning circuit converts the raw electrical quantity into a useful electrical quantity. 3: An analog-to-digital converter (ADC) converts the useful electrical quantity to information. 4: A buffer and interface store, format, and present the information to a computer. 5: An interface routine reads the information, converts it to the desired form, and stores it in the desired place. 02-1 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli02. 02-1 02-2 02-2 Process State and Process Variables The process state is the current condition of the process, down to infinitesimal detail. The process variable is a part or characterization of a process state, usually in terms of a common measure. For example, consider a coffee maker. Process state: amount of water in carafe, water temperature, chemical description of water in carafe, type of coffee beans, etc. Process variable: temperature of water. Process variable value: 70 C. Characteristics It is impossible to know the complete process state (because of infinite detail). It is impossible to know the exact value of a process variable. A process variable value, however, can be determined to a high degree of precision. 02-2 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli02. 02-2 02-3 02-3 Dimensions Basics A process variables value is usually expressed as the product of a number and a dimension. For example, let process variable T be the temperature of water in a coffee maker carafe. Then a value for T might be 60 C. An equivalent value might be T = 333 . 15 K. Notation Dimensions will be written in Roman (upright) type. For example, mA, V, and m. Symbols representing values (variables) will be written in italic type: T , x , and R . Thus, 3 V V means three vee volts. 02-3 EE 4770 Lecture Transparency. Formatted 13:25, 23 December 1997 from lsli02. 02-3 02-4 02-4 Algebraic Manipulation of Dimensions In expressions, dimensions are manipulated in the same way as num- bers and variables....
View Full Document

Page1 / 4

lsli02.4up - 02-1 02-1 Process State, Sensors, and...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online