Vaisala DMT143 - Manual (Page 19)

Chapter 3 _______________________________________________________ Functional Description
VAISALA ________________________________________________________________________ 17
DMT143 Startup Sequence
When the transmitter is powered up, it will perform the sequence
(applicable from software version 1.1.5 onward) shown in Figure 4
below. After a two-second startup, the transmitter will measure normally
for forty seconds, after which it will perform the sensor purge and auto-
calibration functions. This can take up to five minutes, during which time
the output is frozen: it will display the last measured values before the
sensor purge began.
The auto-calibration function may be postponed if the measurement
environment is not suitable. For example, the environment may be
changing rapidly or have too high humidity.
Normal operation and output is typically achieved no later than six
minutes after startup. The sensor purge will repeat every 24 hours, and
auto-calibration every hour. The output will again be frozen for their
duration.
1401-033
Figure 4 DMT143 Startup Sequence
NOTE The transmitter always performs this sequence when starting up. Keep
the transmitter continuously powered to optimize its measurement
performance and availability.
Normal output Normal output
2 s
Output frozen
40 s 3 ... 5 min
Time
Purge*
3 min
Autocal**
<2 min
* Purge will repeat every 24 hours
** Autocal will repeat every 60 minutes (is postponed if environment is not suitable)
Startup