IM 01C25T02-01E
6-10
6. EXPLANATION OF BASIC ITEMS
6.5 AI Function Block
The AI function block is a unit of the software and
executed according to the system schedule. During
execution, it incorporates data from the SENSOR
transducer block. After execution, it updates analog
outputs and processes newly generated alarms. AI
function blocks can provide a discrete output which
shows the status of LO, LO_LO, HI, or HI_HI. In
terms of function, there is no difference between the
three AI function blocks provided in EJX.
6.5.1 Function Blocks
The AI function block, via the Channel, incorporates
analog signals from the transducer block, performs
scaling processing, filtering, low-cut, and alarm
processing before outputting. It has the function to
generate a discrete output. Figure 6.4 presents the AI
function block.
6.5.2 Block Mode
The Block modes permitted for the AI function block
are Automatic (Auto), Manual (Man), and Out of
Service (O/S). When the Block mode of RB (Resource
Block) is Out of Service (O/S), Actual is Out of
Service (O/S) even if Automatic (Auto) or Manual
(Man) is written to Target.
6.5.3 IO_OPTS
IO_OPTS is a parameter used to select whether options
regarding input and output signals should be enabled or
disabled. In the case of the AI function block, the only
available option is “Low cutoff”. When enabling the
low cut function for outputs, set this option.
6.5.4 STATUS_OPT
STATUS_OPT is a parameter to select options
regarding the status of signals. The AI function block
offers four options: Propagate Fault Forward, Uncertain
if Limited, BAD if Limited, and Uncertain if Man
mode.
Propagate Fault Forward
If the status from the sensor is Bad, Device failure or
Bad, Sensor failure, propagate it to OUT without
generating an alarm. The use of these sub-statuses in
OUT is determined by this option. Through this option,
the user may determine whether alarming (sending of
an alert) will be done by the block or propagated
downstream for alarming
Uncertain if Man mode
When the “Uncertain if Man” is enabled and the
Actual mode is Man, the OUT signal status should be
“Uncertain”.
Scaling
OUT_SCALE
Filter
PV_FTIME
Cutoff
LOW_CUT
L_TYPE
Simulate
SIMULATE.
Transducer Value
SIMULATE.Enable
Simulate
SIMULATE.
Simulate Value
Scaling
XD_SCALE
FIELD_VAL.Value
IO_OPTS.Low cutoff
OUT_D_SEL
PV.Value
MODE_BLK.Actual
Alarms
LO, LO_LO
HI, HI_HI
冑苳
/100
/100
Disable Enable
Direct
Indirect
=0(Disable)
Auto
=1(Enable)
OUT
OUT_D
Ind.Sqr Root
F0608.EPS
Figure 6.4 Diagram of the AI Functional Block
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