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DCP200 Profile Controller & Recorder - Product Manual
Page 158 Glossary 51-52-25-150, Issue 1 – April 2009
RTD
Resistance Temperature Detector. A temperature sensor that changes resistance with a
change in the measured temperature. This instruments process input supports PT100
(platinum, 100Ω at 0°C) and NI120 (nickel, 120Ω at 0°C) sensors. These have positive
temperature coefficients (PTC) which means their resistance increases with higher
temperatures. The temperature measured by the sensor can be displayed as °C; °F or °K.
Also refer to: Input Range, Process Input and Thermocouple.
Scale Range Upper Limit
For linear inputs, this parameter is used to scale the displayed process variable. It defines
the displayed value when the process variable input is at its maximum value (e.g. if 4 to
20mA represents 0 to 14pH, this parameter should be set to 14). The value can be set
anywhere from -1999 to 9999 and can be set to a value less than (but not within 100 LSDs
of) the Scale Range Lower Limit, in which case the sense of the input is reversed.
Settings = -1999 to 9999 Default value = 1000.
For thermocouple and RTD inputs, this parameter is used to reduce the effective span of the
input. All span related functions work from the trimmed input span. The parameter can be
adjusted within the limits of the range, but not less than 100 LSD’s above the Scale Range
Lower Limit.
Settings = Range Max to Min. Default value = Max value of selected temperature range).
Also refer to: Engineering Units, Input Range, Input Span, LSD, Process Variable and Scale
Range Lower Limit.
Scale Range Lower Limit
For linear inputs, this parameter is used to scale the displayed process variable. It defines
the displayed value when the process variable input is at its minimum value (e.g. if 4 to 20mA
represents 0 to 14pH, this parameter should be set to 0). The value can be set from -1999 to
9999 and can be set to a value higher than (but not within 100 LSDs of) the Scale Range
Upper Limit, in which case the sense of the input is reversed.
Settings = -1999 to 9999 Default value = 0.
For thermocouple and RTD inputs, this parameter is used to reduce the effective range of the
input. All span related functions work from the trimmed input span. The parameter can be
adjusted within the limits of the range, but not less than 100 LSD’s below the Scale Range
Upper Limit.
Settings = Range Max to Min. Default value = Min value of selected temperature range).
Also refer to: Engineering Units, Input Range, Input Span, LSD, Process Variable and Scale
Range Upper Limit.
Secondary Proportional Band
The portion of the input span over which the Secondary Output power level is proportional to
the process variable value. The Control action for the Secondary Output is always the
opposite of the Primary output. The Secondary Proportional Band is only applicable when
Dual Control Type is used.
Settings = On-Off Control or 0.5% to 999.9% Default Value = 10%.
Also refer to: Control Action, Control Type, On-Off Control, Input Span, Overlap/Deadband,
PID, Primary Proportional Band and Tuning.