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Rosemount Models 244EH and 244ER PC-Programmable Temperature Transmitters
3-8
Figure 4-1 illustrates an example of intermittent sensor detect with
damping enabled. If the temperature undergoes a step change greater
than the threshold value, or from 100 degrees to 110 degrees, and the
damping is set to 5.0 seconds, the transmitter calculates a new reading
every 500 ms using the damping equation, but holds the output at
100 degrees for between 1.75 and 2.0 seconds. Within 1.75 and
2.0 seconds, the transmitter outputs the reading that corresponds to
the damping curve at that time (
), and continues to calculate and
update the output reading every 500 ms thereafter (
) according to the
damping equation. After 5 seconds, the transmitter outputs
106.3 degrees, or 63% of the input change (
), and the output
continues to approach the input curve according to the equation above.
NOTE
If the damping time constant is set between 0 and 2 seconds, the
transmitter does not report the output change until the intermittent
sensor algorithm validates the input signal. After validating the input
signal, the transmitter outputs the value that corresponds to the
damping curve at that time.
Figure 3-3. Damping Function when
Input Change is Greater Than the
Threshold Value
Intermittent Sensor Detect
(Advanced Feature)
NOTE
The Intermittent Sensor Detect feature is not available when using a
Model 244EH with software revision 5.5.1. To determine the software
version of a Model 244E temperature transmitter, first connect the
transmitter to the Model 244EC configurator, open the Model 244EC
software configuration tool, and then choose “service” from the Model
244EC software menu.
The Intermittent Sensor Detect feature is designed to guard against
process temperature readings caused by intermittent open sensor
conditions (an intermittent sensor condition is an open sensor condition
that lasts less than 0.7 seconds). By default, the transmitter is shipped
with the Intermittent Sensor Detect feature switched ON. In most
applications, this is the preferred setting. The Intermittent Sensor
Detect feature can be switched ON or OFF with the Model 244EC. The
setting of this feature cannot be changed when using a Model 244E
with version 5.5.1 software and a Model 244EC version 2.0 or earlier.
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