National Instruments NI-FBUS - Manual (Page 146)

Glossary
NI-FBUS Configurator User Manual G-10 ni.com
Stale Data that has not been updated for stale_limit number of
macrocycles, where the stale limit is a parameter of the connection.
Subscriber A device that has at least one function block with its input value
connected to the output of another device.
Symbol file A Fieldbus Foundation or device manufacturer-supplied file that
contains the ASCII names for all the objects in a device.
T
Tag A name you can define for a block, virtual field device, or device.
Timeout A period of time after which an error condition is raised if some event
has not occurred.
Traditional system See 4-20 mA system .
Transducer block A block that is an interface to the physical, sensing hardware in
the device. It also performs the digitizing, filtering, and scaling
conversions needed to present input data to function blocks, and
converts output data from function blocks. Transducer blocks
decouple the function blocks from the hardware details of a given
device, allowing generic indication of function block input and
output. Manufacturers can define their own transducer blocks.
Trend A Fieldbus object that allows a device to sample a process variable
periodically, then transmit a history of the values on the network.
Trend function An NI-FBUS call related to trends.
U
Unscheduled Messages sent on the Fieldbus between transmissions of scheduled
messages.
Upstream Fewer network hops away from a backbone or hub. For example, a
small ISP that connects to the Internet through a larger ISP that has
their own connection to the backbone is downstream from the larger
ISP, and the larger ISP is upstream from the smaller ISP.