Allen-Bradley 1757-FFLD2, User Manual

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Rockwell Automation Publication 1757-UM012A-EN-P - July 2011 175
Glossary
linking device
As a bridge, enables peer-to-peer communication between H1 devices without
the need for host system intervention. As a gateway, connects the HSE network
to other plant control and information networks.
link active scheduler
Abbreviated as LAS, this scheduler is responsible for coordinating all
communication on the fieldbus; maintaining a list of transmission times for all
data buffers in all devices that need to be cyclically transmitted. The LAS, which
resides in the H1 interface card, circulates tokens, distributes time, probes for new
devices, and removes non-responsive devices from the link.
link master
An LM is a device that contains LAS functionality that can control
communication on a FOUNDATION fieldbus H1 fieldbus link.
There must be at least one LM on the H1 link; one of those LM devices is
chosen as the LAS.
link objects Link object contains information to link function block input/output parameters
in the same device and between different devices. The link object links directly to
a virtual communication relationship (VCR)
logical component Function blocks and algorithms that control a project.
logix block Facilitates signals between a ControlLogix environment and a fieldbus
environment to link control.
macrocycle
Automatically calculated time by RSFieldbus software for a fieldbus device to
send and receive data. The LAS is responsible for scheduling of the segment
macrocycle.
MAN
Abbreviation for manual.
mode
Control block operational condition, such as manual, automatic, or cascade.
network
A network as applied in this document is the termination of one or more
fieldbus segments into an interface card of the Host system.
node The connection point at which media access is provided.
object dictionary Contains all function block, resource block, and transducer block parameters that
are used in a device. Through these parameters, the blocks may be accessed over
the fieldbus network.
OPC
Acronym for OPen Connectivity, formerly Object Linking and Embedding for
Process Control. It’s a software application that lets a bi-directional data flow
between two separate applications. These applications may be running on the
same or separate servers.
offline Perform tasks while the Host system is not communicating with the
field devices.