West Control Solutions ProVU 4 - Manual (Page 141)

ProVU4 Controller, Profiler & Recorder/Controller - Product Manual
Page 140 Glossary 59407, Issue 1 – March 2008
Deviation Alarm Value
Defines the amount of control deviation considered acceptable before a deviation alarm is
activated. A positive value (deviation high) sets the alarm point above the current actual
setpoint, a negative value (deviation low) sets the alarm point below actual setpoint. If the
process variable deviates from the actual setpoint by a margin greater than this value, the
deviation alarm becomes active. If an alarm is required if the control deviation is either side
of the setpoint, consider using a Band alarm or a logical combination of a deviation high and
deviation low alarm.
Settings = 1 LSD to full span from the setpoint
Default value = 5 LSD’s.
Also refer to: Actual Setpoint, Alarm Operation, Alarm Types, Band Alarm, Control Deviation,
Logical Combination, Process Variable and Setpoint.
Digital Input
An input that can be driven to one of two states (active or inactive) by and external voltage or
a contact opening/closing. Digital Inputs can be used to set the instrument in to different
states. Possible uses are to select Auto/Manual Mode, Active Setpoint, Control Enable,
Profile Run/Hold/Abort, Hold Segment Release and Recording Start/Stop.
Also refer to: Active Setpoint, Control Enable, Data Recording, Manual Mode, Profiling and
Segment Types.
Direct Acting Control
Direct action is required for applications where the primary control output will be used to
force the process variable down towards the setpoint. A typical application is a Chiller. When
the control action is selected as direct acting, primary proportional control outputs decrease
the correcting variable as the process variable reduces within the proportional band, and
primary On-Off outputs turn off when the process variable is less than the setpoint. The
control action of a secondary output is always the opposite of the primary output.
Also refer to: Control Action, Control Type, Correcting Variable, On-Off Control, Process
Variable, Proportional Control and Reverse Acting Control.
Display Configuration
A sub-menu of Configuration Mode used to adjust the display, and the parameters that relate
to Operation Mode (Custom display enable, read-only operation mode, bar-graph formatting,
trend setup, display colour & contrast and language selection).
Also refer to: Bar-Graphs, Configuration Mode, Custom Display Mode, Operation Mode, Main
Menu and Trend Display.
Display Languages
The instrument supports two languages. A main language and an alternative language. The
user can order the main language of their choice (current supported languages are English,
French, German, Italian, Spanish and Russian). In most cases the alternative language is
English (for English main the alternative is German). The user can change the language
used by downloading a new file from the PC software.
Also refer to: Display Configuration, Operation Mode, and Main Menu.