52
80-1403-01, Rev. 3
FOUNDATION FIELDBUS
PARAMETER PRESENTATION
The Beck DCM-3 parameters are accessed
through five Foundation Fieldbus blocks: Resource,
Transducer, Analog Out, Analog In 1, and Analog
In 2. All of the blocks except the Transducer Block
are standard Foundation Fieldbus blocks. The
Transducer block is a custom block, and is the
access path to most Beck‑specific information.
For more information on the other blocks, refer to
Foundation Fieldbus Communication Overview
(page 13).
Foundation Fieldbus networks are able to
access the information in the standard blocks
using data structure information provided by the
Fieldbus Foundation. In order to access the data
in the Transducer Block, a Device Description (DD)
file is required.
The DD is used by fieldbus access tools to
identify Beck‑specific information. The DD for
Foundation Fieldbus contains a set of menus which
are similar to the HART menus, and provides a
data list for the Transducer Block. Depending on
the access tool, the menus may not be available to
the technician. Also, the presentation of the data
list varies significantly from system to system.
Some data in the Transducer Block is contained
in groups of data called Records. Record names
are included in the data list presented here in case
the access tool emphasizes the record structure.
The notation NameA: NameB is intended to
indicate record A contains parameter B.
Some access tools can be customized to
present certain data pieces in certain windows. If
more data appears in the list supplied here than in
the list in the access tool, check alternate windows
or views.
CHANGING PARAMETER
VALUES
Foundation Fieldbus distinguishes between
parameters that are read-write and parameters
that are read-only. There is also a technique of
writing parameters as a command action. The
command actions write values but do not read
values. The Beck DD uses these three parameter
classifications.
Parameters that are read-only cannot be
written at any time. If the fieldbus access tools
provide for automatic updating of values, the
values should update without manual intervention.
The Beck DCM-3 always provides up-to-date
parameter information.
Parameters that are read-write can be changed
by the technician, but changes have restrictions.
Some fieldbus access tools may apply
restrictions based on user names or passwords.
The Beck DCM-3 does not implement restrictions
of this sort.
Foundation Fieldbus allows most changes to
be blocked unless the mode of the block is set to
OOS (Out of Service). The Beck DD uses this OOS
requirement to protect the system from changes
during loop operation. Therefore, parameter writes
are blocked unless the mode is set to OOS.
PARAMETER LISTING
Two presentations of the Transducer Block
are shown on the following pages. The first listing
is in the order the data is listed in the DD. The
second listing is an index to allow a person to find
a parameter by label and then, from that, identify
the data in the first listing.
In the first listing, the Relative Index column is
for reference purposes only, and does not indicate
an exact line count or computer index-value.
Parameters that are members of records
are shown by the record index followed by the
parameter label. Parameters that are not members
of records are shown simply as the label name.
In the second listing, the parameters are
shown in alphabetical order. The Relative Index-
value can be used to find the parameter in the first
listing.
RELATIONSHIP AMONG
BLOCKS
The five Foundation Fieldbus blocks include
three that are function blocks (Analog Out and
two Analog In), the Resource Block, and the
Transducer Block. The Resource Block contains
access to some hardware level functions, but is
not used in normal operation of the DCM-3. The
Transducer Block and the three function blocks
interact to operate the actuator.
In general, the Transducer Block establishes
the configuration of the DCM‑3 and the function
blocks provide real time access for control and
monitoring. The Transducer Block also displays
the real time values some parameters in function
blocks.
FOUNDATION FIELDBUS
Parameters
