VEGA D90 Profibus PA - Manual (Page 31)

Pressure transmitter D90 (Profibus PA) 31
Diagnostics
5 Diagnostics
5.1 Maintenance
Pressure transmitters D90 are maintenance-
free.
5.2 Failure rectification
Fault signals
The pressure transmitter D90 provides maxi-
mum reliability through its self-test and con-
tinuous self-monitoring. If, however, malfunc-
tions occur, the pressure transmitter D90
diagnosis distinguishes between atypical
process conditions and faults in the pressure
transmitter D90.
Atypical process conditions
Exceeding or falling short of measuring
range limits (fault signal extinguishes when
the measured value is again in the measuring
range).
Failure in the D90 pressure transmitter
Failure in the electronics, interference or
damage in the measuring cell.
The following table assists in the analysis of
fault signals.
Cause of Fault signal via
failure DOT-matrix Bar graph
Digital indication
Clearly "OPERATE Bar graph 0 %
outside ???? or 100 %
measuring bar" digital value
range flashes
Overload Bar graph 0 %
range or 100 %,
of the digital value
meas. cell four segments
flash "- - - -"
Failure in all segments
D90 flash
On instruments with menu-driven adjustment
with additional functions, the possible rea-
sons are displayed under the menu item
"Diagnostics no." in case of failure.
Diagnostics Meaning
no.
1 No frequency from C/D-converter
2 Frequency signal of the capacitor not
within the limit values
3 Frequency signal of the reference
capacitor not within the limit values
4 Frequency signal temperature not
within the limit values
7 Communication with EEPROM dis-
rupted
9 Error in EEPROM CRC-checksum
11 Process connection or electronics
module has been exchanged (ap-
pears for approx. 20 s after switching
on for the first time after exchange)
Troubleshooting
If the displayed value does not correspond
to the level in the vessel or to the process
pressure, the following measures must be
taken:
- check the pressure compensation (only
with gauge pressure measuring ranges)
- check the electrical connections.
Checking pressure compensation
Open the processing unit of the D90 pres-
sure transmitter. The measured value must
not change. However, if the displayed value
changes, compensation of the atmospheric
pressure is not ensured and will lead to dis-
tortion of the measured value. Check the
breather on the processing unit.