Process variable measurement and local display with multiple ranges

Abstract

The present invention provides a process variable indicator. The process variable indicator includes a process variable sensor having an electrical characteristic that varies with the process variable. A measurement circuit is connected to the process variable sensor and configured to provide an indication of the electrical characteristic. A processor is connected to the measurement circuit and configured to calculate a process variable based on the indication and determine, among the plurality of ranges, which range the process variable is in. A processor generates local visual output based on the process variable and the determined range. Also provides a way to visually indicate process variables.

Description

technical field

[0001] The present application relates to process variable indicators and methods of visually indicating process variables. Background technique

[0002] Mechanical instruments for measuring and displaying process variables such as pressure or temperature are widely used in industry. These instruments usually do not require any source of electrical power, but instead use mechanical techniques to display their individual process variables. For example, Bourdon tube devices produce movement of a pointer directly in response to pressure changes within the Bourdon tube to which the pointer is exposed. Similarly, a temperature measuring device may have a pointer connected to a bimetallic strip that is sensitive to changes in temperature. These are just two examples of conventional mechanisms that are and will continue to be in process equipment today. By virtue of their mechanical properties, these devices are immune to power failures and are relatively cheap t...

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