Pyromation Series 610 1_16 DIN - Manual (Page 152)

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Offset Type: Controller Parameter
Offset is used to modify the measured process variable value and is adjustable in the range
±input span. Use this parameter to compensate for errors in the displayed process variable.
Positive values are added to the process variable reading, negative values are subtracted.
This parameter is in effect, a calibration adjustment; it MUST be used with care. Injudicious
use could lead to the displayed value bearing no meaningful relationship to the actual
process variable. There is no front panel indication of when this parameter is in use.
Display value =
""- , default value = 0.
Also refer to Input Span, Process Variable and Tare.
On-Off Control Type: Controller Definition
When operating in On-Off control, the output(s) will turn on or off as the process variable
crosses the setpoint in a manner similar to a central heating thermostat. Some oscillation of
the process variable is inevitable when using On-Off control.
On-Off control can be implemented only with Time Proportioning Control (Relay, Triac or
SSR driver output), by setting the corresponding proportional band(s) to zero. On-Off
operation can be assigned to the Primary output alone (secondary output not present),
Primary and Secondary outputs or Secondary output only (with the primary Output set for
time proportional or current proportional control).
On-Off control cannot be used on Valve Motor Drive controllers.
Also refer to Differential, PID, Process Variable, Primary Proportional Band, Secondary
Proportional Band, Setpoint, Time Proportioning Control and Valve Motor Drive Control.
On-Off Differential (Hysteresis) Type: Controller Parameter
Refer to Differential.
Open Loop VMD Type: VMD Controller Definition
An “Open Loop” PID control algorithm does not require a position feedback signal from the
valve in order to correctly control the process. Instead, the Process Variable’s deviation from
the Setpoint is used to decide how long the valve open or close outputs should be energised
(in relation to the Motor Travel Time) in order to bring the process under control.
Even when position feedback is provided for Valve Position Indication, the controller does not
use this signal when positioning the valve, so problems associated with faulty feedback
signals are avoided.
Also refer to Modulating Valve, Motor Travel Time, PID, Process Variable, Setpoint, Valve
Position Indication and Valve Motor Drive Control.
Overlap/Deadband Type: Controller Parameter
Defines the portion of the primary and secondary proportional bands ( ):) + ):- ) over
which both outputs are active (Overlap), or neither is active (Deadband). It is adjustable in
the range -20% to +20% of the two proportional bands added together. Positive values =
Overlap, negative values = Deadband.
This parameter is not applicable if the primary output is set for On-Off control or there is no
Secondary Output. If the Secondary Output is set for On-Off, this parameter has the effect of
moving the Differential band of the Secondary Output to create the overlap or deadband.
When Overlap/Deadband = 0, the “OFF” edge of the Secondary Output Differential band
coincides with the point at which the Primary Output = 0%. ).
Display code =
' , default value = 0%.
Also refer to Differential, On-Off Control, Primary Proportional Band and Secondary
Proportional Band.
59305, Issue 6 – March 2006
Glossary Page 147