Technical Specifications

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Controller Parameters Tab
Ratio Gain and Bias In ratio control, the setpoint and process variable may be in differ-
ent engineering units or on different scales. The relationship
between the setpoint in process variable units and the raw set-
point is given by:
Setpoint (in process variable units) = Ratio Gain x Setpoint (in its
units) + Ratio Bias
Setpoint Low and High
Limit
The setpoint is constrained to be between the low and high limits.
The limits are entered in the same engineering unit as the control-
ler unit.
Proportional Gain The ratio of controller output to the error. The relationship between
the Proportional Gain and the Proportional Band is: PB in % = 100 /
PG. The range is 0 to 50. The Proportional Gain can be adjusted by
the Beta coefficient.
Integral Time (s) Or reset time, is the time constant of integral control. The range is 0
to 1000 second.
Derivative Time (ms) Derivative time or rate time is the time constant of derivative con-
trol. The range is 0 to 5000 millisecond.
Derivative Gain This is a parameter to control the Derivative Time. The range is 0 to
100. This coefficient act as a first order filter on the Derivative Time.
Beta (non-linear) This is non-linear gain factor, ranging from -9 to 9. When 0, the
controller gain is linear. Otherwise the gain is the function of error.
Low Alarm Limit and High
Alarm Limit
Define when the alarm lights on the controller view are lit. If abso-
lute alarms are selected and the process variable is not between
the low and high alarm limit, the alarm light is on. If deviation
alarms are set and the difference between the setpoint and the
process variable is not between the low and high alarm limit, the
alarm light is on. The alarm limits are entered in the same units as
the process variable.
Manual Reset Bias (%) This mainly applies to P or PD control or unstable (integrator) pro-
cess. It is the process controller output at a typical operating
steady state. If the controller outputs range goes from 30 to 50%
at normal operation, the Manual Reset Bias should be set at 40% in
order to minimize steady state error.
Output Rate limit (%/s) Limits how fast the controller output can change. It is expressed as
the percent of full controller output range per second and can be
set up to 500%/s.
Controller Dead Zone (%) When the difference between the setpoint and the process vari-
able is less than the dead zone, the controller takes no action to
change this output. The range is 0% to 20%.