Technical Specifications

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Damping Coefficient The valve response may be made slower for some applications.
A value of 0 gives no damping, and a value of 9 gives maximum
damping of valve motion.
Data Link Layer (DLL) This controls transmission of messages onto the fieldbus, and
manages access to the fieldbus through the Link Active Sched-
uler (LAS). The DLL used by FOUNDATION Fieldbus is defined
in IEC 61158 and ISA S50. It includes Publisher/Subscriber, Cli-
ent/Server and Source/Sink services.
DD See Device Description
Dead Zone(%) When the valve position is within the setpoint +/- the dead zone,
no additional position control occurs. This value is normally 0%,
however for high friction valves (e.g. valves with graphite pack-
ing) a higher dead zone helps avoid limit cycling due to the
stick/slip action of the valve. In these cases the dead zone cho-
sen might be 0.2% to 1%.
Decimal Notation for numbers to base 10. The number sequence is
0,1...9.
Device Description
(DD)
This provides an extended description of each object in the Vir-
tual Field Device (VFD), and includes information needed for a
control system or host to understand VFD data meaning.
DI Digital Input Block
Dialog
This is the term for a screen that allows you to interface with the
software application.
DLL Dynamic Link Library in Windows. DLL files are installed when
installing NIFB software and ValVueFF software.
FAS Fieldbus Access
Sublayer
A Fieldbus is a digital, two-way, multi-drop communication link
among intelligent measurement and control devices. It serves
as a Local Area Network (LAN) for advanced process control,
remote input/output and high speed factory automation applica-
tions.
Fieldbus Access
Sublayer (FAS)
The Fieldbus Access Sublayer (FAS) maps the Fieldbus Mes-
sage Specification (FMS) onto the Data Link Layer (DLL).
Fieldbus Messaging
Specification (FMS)
This contains definitions of Application Layer services in FOUN-
DATION Fieldbus. The FMS specifies services and message
formats for accessing Function Block (FB) parameters, as well
as Object Dictionary (OD) descriptions for those parameters
defined in the Virtual Field Device (VFD).
Flash Memory A computer memory which is not volatile. It stores all its data
even when the power is off. It performs high speed reads and
may be re-written many times. It is used to store programs and
permanent parameters.