Proline Promag 55 PROFIBUS DP/PA Commissioning
Endress+Hauser 85
Triggering warning messages
A limit value may be assigned to all diagnostic parameters if necessary. If this limit value is exceeded,
a warning message is triggered WARNING MODE function (7503).
The limit value is entered into the measuring system as an absolute (+/–) or relative deviation
compared to the reference value WARNING function (75...).
Deviations which occur and which are recorded by the measuring system can also be output via the
current or relay outputs.
Data interpretation
The interpretation of the data recorded by the measuring system depends greatly on the application
in question. This requires an exact knowledge of the process conditions and the associated deviation
tolerances in the process which must be determined individually by the user.
For example, to apply the limit value function (ACTUAL DEVIATION), a knowledge of the
permitted minimum and maximum deviation tolerances is particularly important. Otherwise, there
is a risk that a warning message could be triggered unintentionally in the event of "normal" process
fluctuations.
Deviations from the reference condition may be caused by different factors. The following table
shows examples and notes for each of the six recorded diagnostic parameters:
!
Note!
To assess possible build-up, the diagnostic parameters of the COATING 1 and COATING 2 function
groups should be interpreted only in combination with those of ELECTRODE POTENTIAL 1 and 2
and VOLUME FLOW. As build-up typically develops over a period of months, it is useful to present
and analyze the relevant measurement data and parameters using appropriate software, for example
using the Endress+Hauser software packages FieldCare with the Flow Communication
FXA193/291 DTM and Fieldsafe Module.
Function group
(diagnostic parameters)
Possible causes in the event of deviations from the reference value
COATING 1 A deviation from the reference value may be caused by the following:
• Build-up on measuring electrode 1
• Electrical outage
• Short-circuit
COATING 2 A deviation from the reference value may be caused by the following:
• Build-up on measuring electrode 2
• Electrical outage
• Short-circuit
ELECTRODE POTENTIAL 1 A change in the electrode potential may be caused by the following:
• Corrosion at measuring electrode 1
• Greater pH fluctuations in the fluid
• Presence of air bubbles at measuring electrode 1
• Mechanical shock effect on the measuring electrode due to solids
• Electrical outage
• Short-circuit
ELECTRODE POTENTIAL 2 A change in the electrode potential may be caused by the following:
• Corrosion at measuring electrode 2
• Greater pH fluctuations in the fluid
• Presence of air bubbles at measuring electrode 2
• Mechanical shock effect on the measuring electrode due to solids
• Electrical outage
• Short-circuit
VOLUME FLOW The volume flow is additional information that is needed to assess the other diagnostic
parameters sufficiently.
NOISE VALUE A change in the noise value may be caused by the following:
• Corrosion at the measuring or reference electrode
• Presence of air bubbles
• Mechanical shock effect on the measuring electrodes due to solids
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