Introduction
Unmanned weather stations
play an essential role in the effort to analyze and
predict the world's ever-changing weather patterns.
The unmanned stations collect and store large amounts
of weather data and then download the data at regular
intervals to a back-end host for analysis and long-term
storage. The computing device housed in the weather
station must be robust enough to work continuously
for long periods of time while exposed to a wide range
of temperatures. It should also be able to collect
readings from various sensors that use different data
transmission protocols, and have the capability to
store large amounts
of data.
Protocol Conversion
and Front-end Data Processing
The data collected by a typical unmanned weather station
includes temperature, rainfall and snow accumulation,
air pressure, humidity, and ultraviolet intensity. One
of the
tasks that
the UC-7420 unit must handle is protocol conversion, since
there is no guarantee that the devices collecting the weather
data all use the same protocol. In addition, the UC-7420
can be used to do preliminary data processing before downloading
data to the central computer. MOXA's UC-7420 is ideally
suited for these tasks, since the user can easily embed
a C program that is custom written for the devices used
at the station. If future changes involve adding or removing
devices, the programmer simply needs to modify the C code,
recompile it, and then download the executable program
over the network to the UC-7420 unit.
Connecting to the Network and the Internet
In addition to being programmable, the UC-7420 also offers
users an array of connection options. To begin with,
data
entering the serial ports from attached sensors can be
processed and then forwarded through one or both of the
dual Ethernet ports to the LAN. One of the serial ports
can also be connected to a V.90 or GPRS modem for PPP
connections, and a PCMCIA port is available for installing
a wireless LAN card for 802.11b/g networks. By including
multiple connection options in the UC-7420's design,
user's gain the flexibility needed to connect from virtually
anywhere.
Combinations of connection types can also be used to
provide redundancy. For example, if unavoidable network
problems cause an interruption in service, the user can
connect by modem.
CompactFlash Storage Space
One of the dilemmas faced when creating a "small" computer
is how to provide users with adequate storage space. For
unmanned applications, it is best if the storage device
does not contain moving parts. Although hard drives may
seem to last forever for day-to-day use,
we cannot make
this assumption for
continuous use at remote locations. The UC-7420 overcomes
this problem by providing a CompactFlash slot. If needed,
flash
memory cards with storage capacity of up to several gigabytes
can be used to store data until it is convenient to transfer
the data to a central computer.
Benefits
- No fan, no hard drive design for longer MTBF
- CompactFlash slot
for adding gigabytes of storage space
- Multiple connection options for greater networking versatility
- Programmability gives system integrators infinite possibilities
- Maintenance personnel can monitor from a remote location
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