Yokogawa YVP110 - Manual (Page 99)

<17. IS Function Block>
17-13
IM 21B04C01-01E
17.4.3 STATUS_OPTS
Bit Description
Use Uncertain as
Good
Causes all inputs (OP_SELECT,
IN_n, and DISABLE_n) the
status of which is “uncertain,”
to be handled as “good” (NC)
status inputs and the others to be
handled as ”bad” status inputs.
Uncertain if Man
mode
When the mode is Man, the
status of OUT is interpreted as
“uncertain.” (This does not apply to
SELECTED.)
17.5 Application Example
The following describes the temperature control
system of a fixed bed-type reactor. In this case,
there are instances where the point showing the
maximum temperature changes due to catalytic
deterioration, raw material flow, etc. Therefore, a
large number of measurement points are provided,
and the maximum value obtained among these
measurement points is input to the controller to
control reactor temperature.
F1710.ai
IS
PID
AI3
AI1
AI2
AI4 AO
Refrigerant
Raw material
Product
C
ata
lyti
c r
ea
cto
r
Figure 17.10 Temperature Control System of a Fixed
Bed-type Reactor
IS
IN_1 4 OUT
PID
BKCAL_IN
OUT IN
AO
CAS_IN
BKCAL_OUT
AI1
OUT
AI1
OUT
AI
OUT
AI1
OUT
AI1 AI4
F1711.ai
Figure 17.11 Example of Scheduling
AI1: Temperature 1, AI2: Temperature 2,
AI3: Temperature 3, AI4: Temperature 4
IS: SELECT_TYPE = MAX
Basic operations and work sequence:
1. The IS block obtains values and status
information from AI.
2. The block selects the AI information using the
alternatives.
3. The block displays and outputs the information
selected by SELECTED.