National Instruments FP-3000 - Manual (Page 141)

Glossary
© National Instruments Corporation Glossary-9 FieldPoint FP-3000 User Manual
Signal An extension of the IEEE 488.2 standard that defines a standard
programming command set and syntax for device-specific
operations.
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.
T
Tag A name you can define for a block, virtual field device, or device.
Terminator A device used to absorb the signal at the end of a wire.
Timeout A period of time after which an error condition is raised if some event
has not occurred.
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.
Trunk See Homerun.
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.