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92 UDC 3300 Process Controller Product Manual 4/00
4.6 Algorithm Data Set Up Group
Introduction
This data deals with various algorithms residing in the controller:
• Control algorithms,
• Input Math algorithms,
• selecting the 1 or 2 PID Loops,
• Output Override,
• 2 Eight Segment Characterizers,
• the Timer function,
• Totalizer function, and
• Gain Scheduling.
ATTENTION Math option (two algorithms, two characterizers, totalizer)
and Two Loops of Control are only available on Expanded Model
DC330E.
Algorithm group
prompts
Table 4-5 lists all the function prompts in the Algorithm Set Up group and
their definitions.
Table 4-5 Algorithm Group Definitions
Lower Display
Prompt
Upper Display
Range of Setting
or Selection
Parameter
Definition
CONT ALG
The CONTROL ALGORITHM lets you select the type of
control that is best for your process.
ON-OFF ON/OFF is the simplest control type. The output can be
either ON (100 %) or OFF (0 %). The Process Variable
(PV) is compared with the setpoint (SP) to determine the
sign of the error (ERROR = PV–SP). The ON/OFF
algorithm operates on the sign of the error signal.
In Direct Acting Control, when the error signal is positive,
the output is 100 %; and when the error signal is negative,
the output is 0 %. If the control action is reverse, the
opposite is true. An adjustable overlap (Hysteresis Band)
is provided between the on and off states.
Other prompts affected: OUT HYST
DUPLEX ON/OFF is an extension of this algorithm when
the output is configured for Duplex. It allows the operation
of a second ON/OFF output. There is a deadband
between the operating ranges of the two inputs and an
adjustable overlap (hysteresis) of the on and off states of
each output. Both Deadband and Hysteresis are
separately adjustable. With no relay action the controller
will read 50 %.
Other prompts affected: OUT HYST and DEADBAND