Siemens SITRANS P DS III Operating Instructions Manual page 117

BAD/CONSTANT status
All inactive device variables have CONSTANT/BAD status.
If a variable having the BAD status is an output value for calculation, the measured value is
BAD.
The basic measured values, namely pressure and temperatures, have the BAD status in the
following cases:
● The analog-to-digital converter does not function.
● Linearization values in the EEPROM are defective.
● If the two end points of the customized characteristic curve are exceeded for the status of
UNCERTAIN status
If a pressure value exceeds or falls below the sensor limits of the device by more than 20%,
the corresponding measured value and the variables inferred from it are UNCERTAIN.
If the analog-to-digital converter for pressure control is over/underrange, the status is
UNCERTAIN.
HIGH LIMIT and LOW LIMIT
If the analog-to-digital converter is overrange, the HIGH LIMIT label is allocated. If the
analog-to-digital converter is underrange, the LOW LIMIT label is allocated.
Change in status
If the status of a device variable changes and it was right at the front of the sequence of
operations for a block, e.g. pressure, then all variables that are derived from it will take on
the same status. In the following example, the device variable "Pressure" has the BAD
status. Since the measuring mode selector is set to "USER", the device variable "User" is
also given the BAD status.
The reasons for changes in the status of a device variable are summarized in the table. If
there were several reasons for a change in status, MANUAL always has the highest priority.
BAD has the second highest and UNCERTAIN the third highest priority.
SITRANS P DS III with HART
Operating Instructions, 06/2013, A5E00047092-09
the device variables of the following function.
Operating functions through HART
7.3 Selecting the measuring modes
117