Technical Specifications

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STOPS FVP The FVPI runs the STOPS procedure to adjust the positioner to
actual valve travel. First the output pressure is reduced to zero,
and the position is recorded. That is the position corresponding
to 0%. The output pressure is raised to its maximum (based on
supply pressure). The position is recorded and corresponds to
100%.
Stroke The total range of valve travel. Often used as a verb to describe
the process of moving the valve.
System Management
(SM)
This synchronizes execution of Function Blocks (FBs) and the
communication of Function Block (FB) parameters on the field-
bus, and handles publication of the time of day to all devices,
automatic assignment of device addresses, and searching for
parameter names or tags on the fieldbus.
Tag The formal designator the control valve used in control loop
documentation.
TB Transducer Block
Terminator This is an impedance-matching module used at or near each
end of a transmission line. Only two Terminators can be used
on a single H1 segment.
Tight Shutoff (TS) A positioner property that is selected and adjusted when it is
desired to prevent operation of the valve at or near the closed
position. The positioner causes all available actuator force to be
applied to the valve seat at a position set point equal to or less
than the TS adjustable parameter. A dead band is applied to
prevent cycling in and out of this behavior.
Transducer Block
(TB)
This decouples Function Blocks (FBs) from the local Input/Out-
put (I/O) functions required to read sensors and command out-
put hardware. Transducer Blocks (TBs) contain information
such as calibration date and sensor type. There is usually one
TRANSDUCER BLOCK (TB) channel for each input or output
of a Function Block (FB).
Transmitter This is an active fieldbus device, usually sensing a physical
variable, containing circuitry which applies a digital signal on the
bus.
Trunk This is the main communication highway between devices on
an H1 fieldbus network. The Trunk acts as a source of main
supply to network spurs.
Unit Index Engineering units in Foundation fieldbus are represented by an
index number, to eliminate confusion. Only listed units with an
assigned unit index are used in function blocks. ValVueFF
always shows the text representation of the unit index.