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On-Line Operation
UMSITRPDS3-1
6.4.19.3 Min/Max Pointer
The maximum positive and negative excursions of the input pressure, sensor temperature, and electronics
temperature are stored in non-volatile memory for later recall. Min/Max pointers are updated during
simulation. Stored values can be reset. Refer to the Online Configuration Map in Appendix for the path to
the min/max pointer and to Figure 6-5 for an example.
FIGURE 6-5 Pressure Min/Max Pointer Example
6.4.19.4 Monitoring the Saturation Current
Transmitter current output in the saturation range can be monitored with a simple limit value component.
This component is configured and activated using the HART Communicator.
Two times need to be configured: response time and hold time. The response time represents the length of
time the current output may remain saturated before an alarm is triggered and the transmitter outputs its
set fault current. The hold time is the duration of the alarm.
In example 1 in Figure 6-6, the response time begins at t1 when the output current, due to an increase in
input pressure, reaches the configured saturation limit. At t2, the response time ends, the hold time begins,
and the transmitter outputs the fault current. At t3, the hold time expires and the alarm is cancelled even
though the current has not dropped below the saturation limit. When the input pressure finally drops, the
transmitter output current decreases from the fault current, through the saturation current and then begins
to follow the input pressure.
In the second example, the duration of the input pressure spike that drives the current output to the
saturation limit is shorter than the configured response time. Consequently, the transmitter will output the
saturation current but not output a fault current.
6-32
November 2005
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