35
Reference Manual
00809-0200-4728, Rev RA
Section 2: Configuration
April 2015
feature can be switched
ON
or
OFF
and the threshold value can be changed to any value
between 0 and 100% of the sensor limits with a Field Communicator.
When the intermittent sensor detection feature is switched
ON
, the transmitter can eliminate
the output pulse caused by intermittent open sensor conditions. Process temperature changes
(T) within the threshold value will be tracked normally by the transmitter’s output. A (T) greater
than the threshold value will activate the intermittent sensor algorithm. True open sensor
conditions will cause the transmitter to go into alarm.
The threshold value of the 644 should be set at a level that allows the normal range of process
temperature fluctuations; too high and the algorithm will not be able to filter out intermittent
conditions; too low and the algorithm will be activated unnecessarily. The default threshold
value is 0.2% of the sensor limits.
When the Intermittent Sensor Detection feature is switched
OFF
, the transmitter tracks all
process temperature changes, even from an intermittent sensor. (The transmitter in effect
behaves as though the threshold value had been set at 100%.) The output delay due to the
intermittent sensor algorithm will be eliminated.
Configure intermittent sensor detection with a Field
Communicator
The following steps indicate how to turn the intermittent sensor detect (or transient filter)
feature
ON
or
OFF
. When the transmitter is connected to a Field Communicator, use the Fast Key
sequence and choose
ON
(normal setting) or
OFF
.
From the
HOME
screen, enter the Fast Key sequence
.
The threshold value can be changed from the default value of 0.2%. Turning the Intermittent
Sensor Detect feature
OFF
or leaving it
ON
and increasing the threshold value above the default
does not affect the time needed for the transmitter to output the correct alarm signal after
detecting a true open sensor condition. However, the transmitter may briefly output a false
temperature reading for up to one update in either direction up to the threshold value (100% of
sensor limits if Intermittent Sensor Detect is
OFF
). Unless a rapid response rate is necessary, the
suggested setting is
ON
with 0.2% threshold.
Configure intermittent sensor detection with AMS Device
Manager
1.
Right click on the device and select
Configure
.
2.
In the left navigation pane select
Manual Setup
.
3.
On the
Device Tab
there will be a group box called Noise Rejection, in the box
Transient Filter Threshold
, enter the desired percent.
4.
Select
Apply
when complete.
Device Dashboard Fast Keys
2, 2, 7, 4, 2
Summary of Contents for Rosemount 644
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