Industrial Square Root Current/Voltage Point Types; Logarithmic Linear Point Types - Omega RD8800 User Manual

Chapter 5 Programming

5.6.8 Industrial Square Root Current/Voltage Point Types

The Recorder accepts five voltage square root extraction ranges: 150mV sqrt, 1.25 Volt sqrt, 2.5 Volt sqrt, 12.5
and 25 Volt sqrt and three types of linear current square root extraction ranges: 4 to 20mA sqrt, 0 to 20mA sqrt
and 10 to 50mA sqrt.
This function is used for inputs which require the Industrial Square Root of the input signal (i.e. flow
measurement). The system calculates the square root of the percentage of input scale and multiplies this
value by the high end scale to produce the value of the point displayed.
In the following example, the input is 4 to 20mA and the scaling is such that 0 = Low End of Scale and 1000 =
High End of Scale.
High End Scale = 1000 gallons per minute
Input Signal = 12mA or 50% of scale which is equal to 0.5
Square Root of 0.5 = 0. 707
Actual value displayed is 0.707 x 1000 = 707 GPM (with Decimal fix of 0)
Current input signals require that the user provide an external resistor.
Programming Parameters - Once a point has been programmed as Industrial Square Root and a voltage or
current mode is selected, the user is presented with the following parameters:
Point tag
Input scale
Output scale
Exc. Currents
Filter
Eng units
Alarms
Chart scale
Output mode

5.6.9 Logarithmic Linear Point Types

The Recorder accepts five types of linear voltage logarithmic ranges: 150mV log, 1.25 Volt log, 2.5 Volt log,
12.5 Volt log and 25 Volt log and three types of linear current logarithmic ranges: 4 to 20mA log, 0 to 20mA log
and 10 to 50mA log.
Programming Parameters - Once a point has been programmed as Log linear and a voltage or current mode
is selected, the user is presented with the following parameters:
Point tag
Input scale
Output scale
Exc. Currents
Filter
Eng units
Alarms
Chart scale
Output mode
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Section 5.6.5.1
Section 5.6.5.2
Section 5.6.5.3
Section 5.6.5.4
Section 5.6.5.6
Section 5.6.5.9
Section 5.6.5.10
Section 5.6.5.11
Section 5.6.5.12
Section 5.6.5.1
Section 5.6.5.2
Section 5.6.5.3 (requires entry of low and high exponents)
Section 5.6.5.4
Section 5.6.5.6
Section 5.6.5.9
Section 5.6.5.10
Section 5.6.5.11
Section 5.6.5.12
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