Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 58)

Publication 1757-UM006A-EN-P - May 2002
2-14 Integrating Fieldbus into Rockwell Automation Logix System
Figure 2.6 Integration of fieldbus device digital input signal with ProcessLogix
control strategy
Fieldbus Discrete Input data manipulation
When the OUT from the fieldbus Discrete Input function block is
wired to the DI[n] input for a DEVCTL function block, the Control
Builder creates a CEE discrete input agent to handle the digital input
from the fieldbus block. The block-like discrete input agent maps the
data structure (DS-66) of the OUT parameter to the ProcessLogix DI[n]
with status parameter. It interprets the value portion in fieldbus terms
as a Boolean for Discrete Input (DI) block and as the appropriate
multi-state representation for special fieldbus Device Control (DC)
block. The value is converted and represented in ProcessLogix at the
output.
The discrete input agent accepts inputs from either a published
parameter or a client/server read parameter, depending upon the
communication method used.
The fieldbus data quality of good(cascade), good(non-cascade), bad,
and uncertain is mapped to the appropriate ProcessLogix parameter
for good, bad, and uncertain.
CM
CPM/CEE
FIM
Fieldbus
Device
FIM
Digital
Input
Transducer
Device
Control
OUT
DI[1]
DO[1]
CEE = Control Execution Environment
FIM = Fieldbus Interface Module
DOC = Digital Output Channel
CM = Control Module
CPM = Control Processor Module
DOC
SO