ABB REM 54 Series, Техническое справочное руководство

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1MRS750915-MUM
Machine Terminal
Technical Reference Manual, General
REM 54_
5.1.9.8. RTD/analog input configuration example
The RTD/analog inputs are supported in the Relay Configuration Tool by the
general measurement function blocks MEAI1...MEAI8. As an example, to monitor
temperature using a PT100 sensor, the measured value of the RTD/analog input is
connected to the function block by connecting the value attribute RTD1_6_AI1 to
the RawAI input of the function block. The output HighAlarm is used to activate a
relay contact when the temperature exceeds a preset limit. The measured
temperature is displayed on the MIMIC view of the HMI by the connected
MMIDATA1 function block. To avoid unnecessary activation of the relay contact
in case of a fault, the corresponding invalid attribute of the RTD/analog input
RTD1_6_AI1IV is connected to the IV input of the function block.
A060253
Fig. 5.1.9.8.-1 RTD/analog input configuration example
5.1.9.9. Self-supervision
Each input sample is validated before it is fed into the filter algorithm. The samples
are validated by measuring an internally set reference voltage immediately after the
inputs are sampled. If the measured offset voltage deviates from the set value more
than 1.5% of the measuring range, the sample is discarded. If the fault continues
longer than for the set filter time, the invalid attributes of all inputs are set to TRUE
to indicate a hardware fault. Should the measurement succeed later, the invalid
attributes are reset to FALSE. This prevents most sudden hardware faults from
affecting the measured value before the invalid attribute is set. To ensure that the
specified measurement accuracy is met, a more thorough test of the hardware is
performed by the continuous recalibration procedure which will catch errors that
degrade the measurement accuracy.