Casella CEL Nomad portable weather station - Manual (Page 19)

4. OPERATION USING A PASSIVE RADIO
LINK BETWEEN PC AND NOMAD
The procedures described in this chapter may be used only with Nomad systems
that are connected to the PC by low power radio link or by a high power radio
link configured for transmission only
"
.
These links are semi-passive systems that transmit data but cannot be
controlled by the PC. Once the Nomad system is storing the required data in the
Sensus data logger, these links will also be transmitting data every 20 seconds
to the radio link on the PC.
When a technician is visiting the Nomad to download the memory in
the field, use the procedures given in Chapter 3.
Assemble the system and deploy the sensors as described in
Chapter 2. Ensure that Online Pro has been installed on the PC and that the
configuration file for the Nomad weather station has also been loaded (see
Chapter 5).
See Chapter 8 for a review of available communication methods.
4.1 Start Logging
When the Sensus data logger was left running after checking the battery voltage
as described in Section 2.3, it will already be logging (storing) data and the
radio transmitting it.
If the battery in-line fuse was removed for transit, or the Sensus data
logger switched off, start logging data to the Sensus as follows.
1. Support the weight of the environmental case door, undo the clips
which hold it shut, then lower the door until the chains support it.
Do not put or hang anything heavy on the lowered door !
2. Replace the in-line fuse if it has been removed.
3. Press key 1 on the Sensus logger (see Figure 1).
When sufficient power is available, shown by activity on the display,
the logger will wait one minute before starting to store data at the rate
specified by the active configuration. The default rate stores data at 5
minute intervals.
The radio will also start to transmit data at 20 second intervals.
The Nomad will continue storing data and the radio link continue
transmitting until stopped by the logger keys or lack of power.
4. Close and re-clip the door of the environmental case.
4.2 Display Real-Time Data
1. Start Online Pro.
2. Select the Open... option from the File menu.
3. Select Display.onl from the Online Pro directory.
This opens the default screens for data viewing.
Operation via Passive Radio Link
Note 4: Because of power constraints, when the Nomad system is powered by the solar panel
and internal battery, it is configured to operate as a semi-passive data transmission
system in the same way as the low power radio link, described in this chapter.
Configuration for full two-way operation with a high power radio link, is possible ONLY
when the Nomad system receives its power from a landline, as described in Chapter 3.
Page 19 of 68
NOMAD Portable Weather Station
Users Handbook