201
dual. For dual control a secondary proportional band
is used for the second output. The control action can
be direct or reverse acting, switching the direction of
change in power relative to the change in PV.
Also refer to: Control Action; Control Type; Overlap/
Deadband; PID; Process Variable; Secondary Propor-
tional Band; and Tuning.
Process High Alarm
An alarm configured to as Process High will activate
once the process has been above the high alarm value
for longer than the alarm minimum duration time. Once
activated, the level must drop below the alarm trigger
point by more than the alarm hysteresis value before it
will deactivate. High alarm activation is not affected by
setpoint changes or the level of control deviation.
Also refer to: Alarm Operation; Alarm Types; Alarm Du-
ration Minimum; Alarm Hysteresis; Control Deviation;
Process Variable and Setpoint.
Process Inputs
The main inputs used to monitor the process value(s)
being controlled. The input are “Universal”, supporting
all common thermocouples, PT100 & NI120 RTDs, po-
tentiometers and DC linear mV, voltage or mA signals.
Linear inputs are compatible with any parameter that
can be converted to a suitable electronic signal. They
can be scaled into engineering units to match the pro-
cess. The 2nd input can also act as an auxiliary input.
Also refer to: Auxiliary Inputs; Engineering Units; Input
Span; PV Offset; Process Variable; Scaled Input Lower
Limit and Scaled Input Upper Limit.
Process Low Alarm n Value
An alarm configured to as Process Low will activate
once the process has been below the low alarm value
for longer than the alarm minimum duration time. Once
activated, the level must rise above the alarm trigger
point by more than the alarm hysteresis value before it
will deactivate. Low alarm activation is not affected by
setpoint changes or the level of control deviation.
Also refer to: Alarm Operation; Alarm Types; Alarm
Duration Minimum; Alarm Hysteresis; Control De-
viation; Process Variable and Setpoint.
Process Variable (PV)
Process Variables are the parameter to be controlled.
Each control loop monitors its PV via one of the pro-
cess inputs. PVs can be any type that can be measured
by these circuits. Common types are thermocouple or
RTD temperature probes, or pressure, level, flow etc
from transducers that convert these parameters into
DC linear input signals (e.g. 4 to 20mA). Linear signals
can be scaled into engineering units using the input
upper & lower limits.
Also refer to: Engineering Units; Input Span; Linear
Input; Process Input; RTD; Scaled Input Lower Limit;
Scaled Input Upper Limit and Thermocouple.
Process Variable Offset
- Refer to Calibration.
Profile Control Menu
If the profiler option is fitted, a profile control menu is
available from the main menu. It allows the user to se-
lect or run a profile, and then control that profile (run,
hold, abort, skip to next segment etc.).
Refer to the Profiler Control Menu information in the
Configuration & Use section.
Also refer to: Main Menu; Profile Setup Menu; Profiler
and Profiler Mode.
Profile Events
Events are outputs that can be made active during
profile segments. Any of the five events tracks can be
configured to be active or inactive for the duration of
each segment, from the profile setup menu. For end
segments, events selected to be stay active until the
unit is powered down or a new profile runs. It is pos-
sible to logically link event and alarms to outputs with a
boolean OR or AND selection.
Also refer to: Alarm Types; Logical Combinations; Pro-
file Segments; Profile Setup Menu; Profiler and Profiler
Mode.
Profile Header
The profile header contains information about how the
profile starts and stops, the power loss recovery ac-
tion, if the profile should repeat multiple times when
run as well as whether the profile runs as a single or
two loop profile.
Refer to the Profile Components information in the Pro-
filer Option section of this manual.
Also refer to: Profile Segments, Profile Setup Menu,
Profiler and Profiler Mode.
Profile Segments
Segments can be ramps, dwells, steps or special seg-
ments such as holds, loop-backs, ends or joins. A max-
imum of 255 segments are possible, shared amongst
up to 64 profiles.
Refer to the Profile Components information in the Pro-
filer Option section of this manual.
Also refer to: Profile Events, Profile Setup Menu, Pro-
filer and Profiler Mode.
Profile Setup Menu
If the Profiler option is fitted, a profile setup menu is
available from the main menu. It allows the user to cre-
ate or edit the profile header and profile segments. Pro-
files can also be deleted from this menu. This menu is
protected by a lock code. Refer to the Profiler Setup
Menu information in the Configuration & Use section.
Also refer to: Lock Codes; Profile Control Menu; Profile
Header; Profile Segments; Profiler and Profiler Mode.
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