West Control Solutions Pro-EC44 - Manual (Page 236)

Pro-EC44 2-Loop Graphical Profile Controller & Recorder
Pro-EC44 Product Manual - 59540-1 October 2013 Page 229
Scaled Input 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 from -
1999 to 9999 and can be set to a value less than (but not within 100 LSDs of) the Scaled
Input Lower Limit, in which case the sense of the input is reversed.
For thermocouple and RTD inputs, it is used to reduce the effective span of the input. All
span related functions work from the trimmed input span. It can be adjusted within the limits
of the range, but not less than 100 LSD’s above the Scaled Input Lower Limit.
Also refer to: Engineering Units; Input Range; Input Span; LSD; Process Variable and Scaled
Input Lower Limit.
Scaled Input 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 Scaled Input
Upper Limit, in which case the sense of the input is reversed.
For thermocouple and RTD inputs, it is used to reduce the effective range of the input. All
span related functions work from the trimmed input span. It can be adjusted within the limits
of the range, but not less than 100 LSD’s below the Scaled Input Upper Limit.
Also refer to: Engineering Units; Input Range; Input Span; LSD; Process Variable and Scaled
Input Upper Limit.
Secondary Proportional Band
If the control type is set to dual, this is 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.
Also refer to: Control Action; Control Type; On-Off Control; Input Span; Overlap/Deadband;
PID; Primary Proportional Band and Tuning.
Self-Tune
Self-Tune continuously optimises tuning while a controller is operating. It monitors control
deviation errors and uses them to calculate new PID values. If the controller is new or the
application has changed, the initial values may be far from ideal, in which case pre-tune can
be used to first establish new initial values. Self-tune will then fine-tune these values. Self-
tune is suspended while pre-tune is running.
Refer to the Automatic Tuning section of this manual for full details.
Also refer to: Control Deviation; Modulating Valves. On-Off Control; Pre-Tune; PI; PID;
Setpoint and Tuning.