Rockwell Automation 1757-FFLDC4 FOUNDATION Fieldbus System User Manual - Manual (Page 176)

176 Rockwell Automation Publication 1757-UM012A-EN-P - July 2011
Glossary
online Perform tasks, such as configuration, while the Host system is communicating
with the field devices.
output parameter A block parameter that sends data to another block.
physical component The hardware of the fieldbus project.
physical layer Physical layer receives messages from the communication stack and converts the
messages into physical signals on the fieldbus transmission medium, and
vice-versa.
PID Acronym for Proportional Integral Derivative.
PV Acronym for Process Variable, which is the primary value.
protocol A set of conventions governing the format and timing of data between
communication devices.
redundancy The duplication of devices for the purpose of enhancing the reliability or
continuity of operations in the event of a failure without loss of a
system function.
resource block (RES) This block controls the linking device. It contains data specific to the linking
device’s hardware. All data is modeled as contained, so there are no links in
this block.
RSFieldbus A graphical software for creating links, loops, and schedules for a process
control network.
RSLogix Software that provides a programming environment for sequential, process, drive,
and motion control programming. The RSLogix environment provides an
IEC 61131-3 compliant interface for controls programming.
segment A physical link (cable) between fieldbus devices and a pair of terminators on
an H1 channel. Segments can be linked by repeaters to form a longer H1 fieldbus.
A fully loaded (maximum number of connected devices) 31.25 Kbps
voltage-mode fieldbus segment should have a total cable length, including spurs,
between any two devices of up to 1900 m. There cannot be a non-redundant
segment between two redundant systems.
setpoint The desired value in a closed-loop feedback system, as in regulation of
temperature or pressure.
standard function block Standard function blocks are built into fieldbus devices as needed to achieve
the desired control functionality. Automation functions provided by standard
function blocks include analog input (AI), analog output (AO), and
proportional integral derivative (PID) control.