Rockwell Automation 1788-CN2FFR EtherNet/IP and ControlNet to FOUNDATION Fieldbus Linking Device - Manual (Page 96)

94 Rockwell Automation Publication 1788-UM057B-EN-P - September 2014
Glossary
online Perform tasks, such as configuration, while the Host system is communicating
with the field devices.
PV Acronym for Process Variable, which is the primary value.
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.
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.
ring bus A network where signals are transmitted from one station and replayed through
each subsequent station in the network. Signal can travel in either direction of the
ring so it creates network redundancy; if the ring breaks in one place the nodes
can still communicate.
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.
signal The event or electrical quantity that conveys information from one point to
another.
tag Unique alphanumeric code assigned to inputs, outputs, equipment items, and
control blocks.
terminator Impedance-matching module used at or near each end of a transmission line that
has the same characteristic impedance of the line. Terminators are used to
minimize signal distortion, which can cause data errors. H1 terminators convert
the current signal transmitted by one device to a voltage signal that can be
received by all devices on the network.
topology The shape and design of the fieldbus network.
transducer block The transducer block decouples function blocks from the local
input/output (I/O) function required to read sensors and command output
hardware. Transducer blocks contain information, such as calibration date and
sensor type. There is usually one transducer block for each input or output of a
function block.
trunk The main communication highway between devices on an H1 fieldbus network.
The trunk acts as a source of main supply to spurs on the network.