Page 114 FOUNDATION Fieldbus ST 700 Pressure Transmitter User's Guide Revision 2.0
Table 33 summarizes the conditions that could cause a non-critical fault in the transmitter along
with recommended actions to correct the fault.
Table 33: Summary of Function blocks Non-critical Faults
Problem/Fault Probable Cause Recommended Action
AI block is
executing, but
status of OUT
parameter is:
Good::[alarm
status]:Constant
AI block is in Manual mode. Write AUTO to
MODE_BLK
parameter of AI block.
AI block is
executing, but
status of OUT
parameter is:
Uncertain::[alarm
status]: inaccurate
Transducer block parameter
CAL_SOURCE = NONE, or a value
of “1” (using default characterization
values).
Recalibrate transmitter
See Calibration
Recalibrate transmitter.
Excess span correction - correction
at CAL_POINT_HI is greater than 5%
of CAL_POINT_HI.
See Calibration
Recalibrate transmitter.
Excess zero correction - correction
at CAL_POINT_LO is greater than
5% of the "URL" (characterized range
of the sensor).
See Calibration for
Zero Correct
Meter-body overload - pressure input
is greater than two times the rated
sensor pressure.
Reduce pressure at
sensor. Check range
and, if required,
replace the transmitter
with one that has a
wider range.
PV value of transducer block is
outside range of XD_SCALE. When
AI block CHANNEL = 1(OR)
OUT value of AI block is outside of
OUT_SCALE range.
Meter body may have
been damaged. Check
the transmitter for
accuracy and linearity.
Replace the meter
body and recalibrate,
if needed.
AI block is
executing, but
status of OUT
parameter is: One
of the following AI
alarms is active in
ALARM_SUM.CUR
RENT
HI_HI, HI, LO, LO_LO - OUT has
crossed the corresponding limit
HI_HI_LIM, HI_LIM, LO_LIM,
LO_LO_LIM, and is either still past
the limit or is in the hysteresis range.
ALARM_HYS is the percentage of
OUT_SCALE that is used for alarm
hysteresis.
Reduce the value or
increase limits.
Block alarm.
Check BLOCK_ERR
for status bit. See
Table 3
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