West Control Solutions ProVU 4 - Manual (Page 148)

ProVU4 Controller, Profiler & Recorder/Controller - Product Manual
59407, Issue 1 – March 2008 Glossary Page 147
Multi-Point Scaling
It the process input is connected to a linear input signal, multi-point can be enabled in the
Input Configuration sub-menu. This allow the linearization of a non-linear signal.
The Scale Range Upper & Lower Limits define the values shown when the input is at
minimum and maximum values, and up to 15 breakpoints can scale input vs. displayed value
between these limits. It is advisable to concentrate these break points in the area of the
range that has the greatest amount of non-linearity, or the area of particular interest in the
application.
Also refer to: Input Configuration, Linear Input, Process Input, Scale Range Lower Limit and
Scale Range Upper Limit.
mVDC
This stands for millivolt DC. It is used in reference to the linear DC millivolt input ranges.
Typically, these will be 0 to 50mVA or 10 to 50mV
Also refer to: Auxiliary Input, Input Range, Linear Input, mADC, Process Variable and VDC
On-Off Control
When operating in On-Off mode, the control 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 Relay, Triac or SSR driver outputs. 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 is selected by setting the
corresponding proportional band(s) to On-Off.
Also refer to: On-Off Differential, PID, Process Variable, Primary Proportional Band,
Secondary Proportional Band, Relay, Setpoint, SSR Driver, Time Proportioning Control and
Triac.
On-Off Differential (On-Off Hysteresis)
A switching differential, centred about the setpoint, when using On-Off control. Relay ‘chatter’
can be eliminated by proper adjustment of this parameter, but too large a value may increase
process variable oscillation to unacceptable levels. On-Off differential is also know as
hysteresis or deadband.
Settings = 0.1% to 10.0% of input span.
Default value = 0.5%.
Also refer to: Input Span, On-Off Control, Process Variable, Relay and Setpoint
Operation Mode
The mode used during normal operation of the instrument. It can be accessed from the Main
Menu, and is the usual mode entered at power-up. The screens shown are incluse a main
screen with bar-graph, a trend view, information about the process, alarms plus optionally,
selection of auto/manual control, control output disabling. Recorder and profiler information
can be displayed if these features are fitted. Up to 50 configuration menu screens can be
defined with the PC software, and will be shown if the Custom Display mode is enabled in
the Display Configuration sub-menu.
Refer to the Operation Mode information in the Configuration & Use section.
Also refer to: Bar-Graphs, Configuration Mode, Custom Display Mode, Display Configuration,
Main Menu, Profiler Setup Menu, Recorder Menu. and Trend Display.