Yokogawa Wireless Temperature Transmitter YTA510 - Manual (Page 9)

<3. About Fieldbus>
3-1
IM 01C50T02-01E
3. About Fieldbus
3.1 Outline
Fieldbus is a bi-directional digital communication
protocol for field devices, which offers an
advancement in implementation technologies for
process control systems and is widely employed by
numerous field devices.
YTA Series Fieldbus communication type employs
the specification standardized by The Fieldbus
Foundation, and provides interoperability between
Yokogawa devices and those produced by other
manufacturers. Fieldbus comes with software
consisting of four AI function blocks and four DI
function blocks, providing the means to implement
a flexible instrumentation system.
For information on other features, engineering,
design, construction work, startup and maintenance
of Fieldbus, refer to “Fieldbus Technical Information”
(TI 38K3A01-01E).
3.2 Internal Structure of YTA
The YTA contains two virtual field devices (VFD)
that share the following functions.
3.2.1 System/network Management VFD
• Sets node addresses and Phisical Device tags
(PD Tag) necessary for communication.
• Controls the execution of function blocks.
• Manages operation parameters and
communication resources (Virtual
Communication Relationship: VCR).
3.2.2 Function Block VFD
(1) Resource block (RS)
• Manages the status of YTA hardware.
• Automatically informs the host of any detected
faults or other problems.
(2) Transducer block (TR)
• Accepts temperature input from sensors and
transfers to AI function block.
• Operates limit swtich calculation and transfers
to DI function block.
(3) AI function block
• Conditions raw data from the Transducer block.
• Outputs temperature signal.
• Carries out scaling, damping and square root
extraction.
(4) DI function block
• Limit switch for temperature.
• Accepts the discrete signal from Transducer
block and Outputs the discrete signal to show if
the temperature exceeds the preset limit.
(5) PID function block
• Performs the PID control computation based on
the deviation of the measured value from the
setpoint.
3.3 Logical Structure of Each
Block
F0301.ai
YTA
Fieldbus
System/network management VFD
Function block VFD
Link Master (option)
PD Tag
Sensor
input
Resource block
Block tag
Parameters
PID function
block (option)
Communication
parameters
VCR
Node address
Function block
execution schedule
DI function
block
Output
AI function
block
Block tag
OUT
Parameters
Transducer
block
Block tag
Parameters
Temperature Sensor
Figure 3.1 Logical Structure of Each Block
Setting of various parameters, node addresses,
and PD Tags shown in Figure 3.1 is required before
starting operation.