COSA Xentaur Xentaur XDTL-HT - Manual (Page 21)

Measurements
21
Measurements
In addition to the sample dew point, the XTDL-HT™ measures sample temperature, sample pressure,
and enclosure temperature. All of these measurements have a set of parameters that can be modified
via the menu and Modbus communication. With the optional I/O board, the XTDL-HT™ can read up to
four external analog inputs that can also be used as measurements.
Each measurement can be configured to trigger an alarm when it goes out of range. The alarm by
default would trigger an error message on the screen. It can also be programmed to trigger a relay (see
Relays chapter). An alarm can be configured as a critical alarm. In this case, the alarm is considered a
system fault.
Measurement value is averaged over a specified period. The averaging buffer sizes can be set via the
menu or via Modbus communication. Increasing the buffer size reduces noise on measurement but it
will also increase the measurement response time.
Moisture Measurement
The XTDL-HT™ measures dew point by detecting the light absorption from moisture molecules at a
specific wavelength. This allows the instrument to react quickly and accurately. However, certain
elements such as CO
2
can affect the moisture measurement. To ensure accurate reading, the XTDL-
HT™ stores calibration curves for multiple gas matrices and it must be configured for the correct gas
matrix in the application. The instrument can hold calibration curves for up to 6 different gas matrices.
Inform COSA Xentaur about your gas matrix when your order is placed.
TruTune™
Once the instrument is calibrated at the factory, no further re-calibration is required. The XTDL-HT™
monitors and re-tunes its circuit daily to ensure peak performance. Tuning generally takes about 2-3
minutes. During this time, the instrument holds the last known dew point measurement. Tuning can
also be initiated manually via the menu. In normal circumstances, there is no need to do so as the unit
automatically tunes itself at midnight daily. However, it may be prudent to initiate manual tuning after
the unit has been inactive for a long period of time, such as reactivating the unit after storage or long
period of maintenance.