Honeywell STT700 STT700 User Manual page 38

SYMPTOM
Unstable onscale "STATUS CHECK = O.K."
input since any identified
problem would give upscale
or downscale fail-safe.
Fail-safe output "CRITICAL STATUS"
signal
Incorrect output "STATUS CHECK = O.K."
signal with but does not correspond to
simulating device value set by simulating
device
"INVALID "INVALID REQUEST"
REQUEST" when
changing LRV or
URV
Non-critical status "USER CORR ACTIVE"
message, without
# sign
Remember that successful communications with the transmitter result in many useful pieces of data. With the
initial I.D. response, the user can confirm that the:
1. Transmitter is powered
2. Line resistance is correct
Wires run to the correct unit. If not, the unit connected can be identified by the tag number.
Page 30
SFC MESSAGE/
DISPLAY
STT700 Temperature Transmitter User's Manual
POSSIBLE CAUSE
Incorrect operating voltage. line resistance is not
Bad sensor wire
connection.
Intermittent open circuit of
sensor.
Wiring disturbed by strong
electromagnetic
interference.
A fail-safe output signal
(critical status) can be
caused by several reasons.
The most common error is
changing the sensor wiring
after probe type selection or
after power-up.
If the LRV is changed, the
URV tries to change by the
same amount to maintain
the same SPAN. If this new
URV exceeds the URL then
this message appears.
Transmitter has been
trimmed for particular
sensor range. This can be
done by keying in
LRV/URV, CORRECT,
ENTER with exact LRV and
URV input values to enable
improved accuracy over the
specifications.
CURE
excessive.
Check connection and wiring
for intermittent connections.
Check that sensor fault
detection is "ON", this allows
detection of a bad sensor.
Protect wiring by using
appropriate grounding,
shielding etc.
The SFC will indicate the
source of the problem by
displaying the appropriate
error message.
Check the appropriate sensor
wiring and power cycle when it
is correct.
Remember when changing
configuration to first connect
sensor wiring correctly, then
change configuration.
Reduce the URV or SPAN
before changing the LRV.
When performing a Reset
Correct command or a sensor
type change, the transmitter
will lose this sensor correction
and fall back to the original
factory calibration.
Revision 1