Yokogawa EJA115 - Manual (Page 15)

IM 01C22T03-00E 3-1
3. ABOUT PROFIBUS PA
3. ABOUT PROFIBUS PA
3.1 Outline
PROFIBUS PA is a widely used bi-directional digital
communication protocol that enables the implementation
of technologically advanced process control systems. The
EJA Series PROFIBUS PA communication type meets
the specifications of PROFIBUS Nutzerorganisation e.V.
and is interoperable with devices from Yokogawa and
other manufacturers.
3.2 Internal Structure of the EJA
The EJA contains four blocks that share the following
functions:
(1) Physical block
• Manages the status of EJA hardware.
(2) Transducer block
• Converts sensor output to pressure signals and
transfers to AI function block.
• Carries out square root extraction.
(3) AI1 function block
• Conditions raw data from the transducer block.
• Outputs differential pressure signals.
• Carries out scaling and damping extraction.
(4) AI2 function block
• Outputs static pressure signals.
3.3 Logical Structure of Each
Block
EJA
Sensor
input
Physical block
Block tag
Parameters
AI function
block
Output
AI function
block
Block tag
OUT
Parameters
Transducer
block
Block tag
Parameters Sensor
F0301.EPS
Figure 3.1 Logical Structure of Each Block
The parameters shown in Figure 3.1 must be set before
starting operation.
3.4 Wiring System Configuration
The number of devices that can be connected to a
single bus and the cable length vary depending on
system design. When constructing systems, both the
basic and overall design must be carefully considered
to allow device performance to be fully exhibited.