Yokogawa YVP20S - Manual (Page 173)

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IM 21B04C50-01E
TA01-4.EPS
The Actuator can be mechanically set to stop at a predetermined position by setting an adjustment,
sometimes with a handwheel or screw stop.
Standard Function
Block (FB) Standard Function Blocks (FBs) are built into fieldbus devices as needed to achieve the desired
control functionality. Automation functions provided by Standard FBs include Analog Input (AI),
Analog Output (AO) and Proportional/Integral/Derivative (PID) control. The Fieldbus Foundation has
released specifications for 21 types of Standard FBs. There can be many types of FBs in a device.
The order and definition of Standard FB parameters are fixed and defined by the specifications.
Trunk A Trunk is 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.
Tag The formal designator the control valve used in control loop documentation.
Quick Opening (see Characteristic)
RB Resource Block
TB Transducer Block
Transmitter A Transmitter is an active fieldbus device, usually sensing a physical variable, containing circuitry
which applies a digital signal on the bus.
Position With a reciprocating valve, the position is the distance of the plug from its seat, normally measured
as a linear motion of the valve or actuator stem. With a rotary valve, the position is the angle of
rotation of the valve plug measured as angular rotation of the valve shaft.
Position, valve
Position limit
The area of a plant where there never is an explosion hazard present, such as the control room or a
wire marshalling rack area. Safe Area
The action of a position with a single pneumatic output for operation with a spring return actuator.
(see double acting). Single Acting
Schedules define when Function Blocks (FBs) execute and when data and status is published on the
bus. Schedules
A Segment is a section of an H1 fieldbus that is terminated in its characteristic impedance.
Segments can be linked by Repeaters to form a longer H1 fieldbus. Each Segment can include up to
32 H1 devices. Segment
A control configuration in which a single control output is sent to two or more control valves. Each
control valve positioner is calibrated to respond to a separate portion of the control signal.
An example would be a steam valve and a cooling water valve arranged to be both closed at 50%
and the steam valve to open Split range
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 will cause 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. Tight Shutoff (TS)
A Transducer Block (TB) decouples Function Blocks (FBs) from the local Input/Output (I/O) functions
required to read sensors and command output hardware. Transducer Blocks (TBs) contain
information such as calibration date and sensor type. There is usually one TB channel for each input
or output of a Function Block (FB). Transducer Block (TB)
System Management (SM) synchronizes execution of Function Blocks (FBs) and the communication
of Function Block (FB) parameters on the fieldbus, 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. System Management
(SM)
A Splice is an H1 Spur measuring less than 1 m (3.28 ft.) in length. Splice
The total range of valve travel. Often used as a verb to describe the process of moving the valve. Stroke
A Spur is an H1 branch line connecting to the Trunk that is a final circuit. A Spur can vary in length
from 1 m (3.28 ft.) to 120 m (394 ft.). Spur
A Terminator 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. Terminator
With a reciprocating valve, the position is the distance of the plug from its seat, normally measured
as a linear motion of the valve or actuator stem. With a rotary valve, the position is the angle of
rotation of the valve plug measured as angular rotation of the valve shaft.
Positioner Tuning
Parameters The positioner requires six integer parameters to determine the response of the positioner to a
setpoint change. Internally, the positioner uses an improved PID control algorithm to control the
valve’s position.
Relay, Pneumatic
Resource Block (RB)
The component which amplifies the pneumatic control signals to provide a wide range of actuation
pressure and to supply and vent at high flow rates for responsive control.
A Resource Block (RB) describes characteristics of the fieldbus device such as the device name,
manufacturer and serial number. There is only one Resource Block (RB) in a device.