ABB Symphony Harmony Series, Instruction, Page: 192 / 402

Function Codes
WBPEEUI240751C0 6 - 13
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While in simulation mode, there is a difference between the
simulation analog output value and the readback output
demand value and the difference is greater than the devia-
tion limit specified in the function code.
In this case, the suspect warns that if the mode is changed
from either override to normal or simulation to normal, the dif-
ference between actual value and override value or between
actual value and simulation value may be significant enough
to cause a process upset.
NOTE: When an IISAC01 Analog Control Station is in manual/over-
ride/auto-bypass mode and is bypassing the analog output of the CIO block,
the suspect status is not set while in override or simulation mode. The station
itself is responsible for preventing the process upset. It accomplishes this by
maintaining bypass control over the analog output until the control output of its
station function block (FC 80) matches the demand output of the station.
Exception Reporting
Each I/O channel function code is an exception reporting
function code. Exception reported data can appear as dynamic
values, alarms, and state changes on displays and in reports
generated by operator interfaces and other system nodes.
Exception reporting is automatic. An I/O channel function
code will generate an exception report periodically to update
data, after a process point reaches a defined alarm limit or
changes state, or after a significant change in value occurs.
The segment control (FC 82) and analog I/O channel function
codes (FC 222 and 224) have specifications that control excep-
tion reporting. Specifically, the segment control function code
contains minimum and maximum exception reporting times
and the I/O channel function codes contain a significant
change specification used to trigger exception reporting.
Engineering Units (EU)
Analog I/O channel function codes automatically perform
engineering unit conversions on analog input, output demand,
and output readback values. Analog inputs and readback val-
ues are converted based on the engineering unit low value,
high value, and EU identifier specifications. Also, input type
and range selection for analog inputs factors into the engineer-
ing units conversion.