P/N: 974153 |
Rev: 072016
|
ECO: 46503
www.dynisco.com
From lab to production,
providing a window into the process
-28-
In a fail-safe condition the PV is not affected and can still be read using the handheld HART
communicator. For process related fail-safe conditions, the transmitter will remain in the alarm state
until the source of error disappears. If certain electronics errors are detected, the fail-safe condition will
latch until a reset is performed by either cycling the power or through a software command.
NAMUR Compliant Saturation and Alarm Values
4 - 20 mA Saturation
4 - 20 mA Alarm
Low
3.8 mA
3.6 mA
High
20.5 mA
>21 mA
You can alter the actual transmitter mA output values by performing an analog output trim using the
HART Communicator.
When a transmitter is in an alarm condition, the analog output displayed by the handheld indicates the
alarm value of the analog output – NOT the value the transmitter would have, if the sensor had not
detected the failure.
Special Conditions and the Corresponding Analog Output
Condition
Alarm Value (fail safe)
EEPROM failure detected
Set to configured fail safe mode
Cold start
Set to fail safe mode low
Pressure above upper limit
Unchanged
Pressure below lower limit
Unchanged
Electronics temp above upper limit
Unchanged
Electronics temp above lower limit
Unchanged
Strain gage open detected
Set to configured fail safe mode
Analog output saturated
Unchanged
Watchdog error detected
Unchanged
Zero/Span Actuator stuck
Set to configured fail safe mode
Low voltage detected
Unchanged
Outside URV or LRV
Unchanged
Rcal simulation on
Unchanged
6.5 ALARM & SATURATION VALUES BURST MODE
No special requirements are defined for the burst mode.
6.6 ALARM & SATURATION VALUES IN MULTIDROP MODE
If the device is in multidrop mode, the NAMUR levels are no longer achievable. Instead the fail safe
condition is indicated by the field device status and the additional diagnostics.
