A HART or 4-20 mA current loop that is powered by a power-supply or digital control
system. The Trex unit is not powering the loop.
FOUNDATION fieldbus
FOUNDATION fieldbus technology uses device descriptions and function blocks to enable
intelligent devices to execute control functions traditionally performed by a distributed
control system.
FOUNDATION fieldbus device
A device that communicates information using the fieldbus protocol on a digital, serial,
multidrop data bus.
FOUNDATION fieldbus Power Plug
A connector with two banana jacks that allows the Trex unit to power a FOUNDATION
fieldbus device. Attach the lead set to the FF terminals, and then attach the FOUNDATION
fieldbus Power Plug to the FF pwr terminal and to the positive (red) FF terminal on top of
the lead set.
HART device
A device that communicates information using the HART protocol.
HART loop
A network that combines an analog signal and digital signal to communicate the process
variable and additional device diagnostics in a master/slave configuration. The network
must have HART or HART-compatible devices and the proper amount of impedance,
which may vary based on the device and network configuration.
HART protocol
Highway Addressable Remote Transducer communication protocol. An industry-standard
protocol for digitally enhanced 4-20 mA communication with devices.
HART tag
An 8-character field used to identify a device. A 32-character long tag is also possible with
HART Universal Revision 6 or higher devices. This field is stored in the HART device and can
be modified.
Intrinsic Safety (IS)
Circuits that are designed to limit the amount of energy consumed or provided to devices
to levels below those that are required to ignite specific types of hazardous materials
under fault and no fault conditions.
It is also a method of providing safe operation of electronic process-control
instrumentation in hazardous areas, such as flammable environments. IS systems keep the
available electrical energy in the system low enough that ignition of the hazardous
atmosphere cannot occur.
Intrinsic Safety barrier
A physical entity that limits the current and voltage into a hazardous area to satisfy
Intrinsic Safety requirements.
Lead set
A cable with two banana plugs to connect the Trex unit to a device.
Link Active Scheduler (LAS)
Glossary
User Guide
September 2021
194 User Guide
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