10 Device Server
Using      the      Vantage      Pro     with     a     Lantronix
UDSâ===========================================================

Connecting a weather station directly to a computer leads to some
risks. A cabled weather station connects to the console through a
rather  long  cable,  so there are plenty of occasions to pick up
very high voltages during thunderstorms. Even if not directly hit

by lightning, voltages much higher than  the  line  driver  built
inâto  the  console of a Vantage Pro can handle can be coupled in
via ground,  or  via  induction. The problem for the computer  is
that  usually  these high voltages also appear at the serial  in‐
terface, possible destroying the interface chips.

The station a Rossboda has a particularly  bad  history  in  this
reâspect.   It  began  as  a  webcam  only site, with the  webcam
mounted in  the interior of the building. The webcam was not  the
problem,  but  the  computer  managing  the images an build  MPEG
videos  from the images was connected via a modem  to  the  phone
line.  The  phone  line  enters the building at a different place
from the power,  so that  in  case  of  ligthning  strikes  some‐
where  near  the building, there were quite high voltages between
the  two.  About  four  or five   modems   have  been  killed  by
lightning,  until  the  phone line was replaced by ISDN. ISDN has
s  no longer the computer that is hit (lighting also destroyed
the exact same  problem,  but  now itâthree motherboards, a  par‐
ticularly  impressive  incident   made   the serial  line  driver
chips explode, one could see the blank chip because  the  plastic

case  exploded), but rather the line  terminaâtion  unit owned by

the telephone company. This unit  has  been  reâplaced  at  least
three times during the last year.

After I installed the Vantage Pro, everything went quite well for
a  while,  winter and spring did not bring any severe storms. But
during summer, the station was hit so badly that the console  was
destroyed,  and  its electronics had to be replaced. The computer
was not affected by this, because the  station  is  not  directly
10 deâ
connected to the computer.  instead, I use a  Lantronix  UDSâvice
server connected to the console via  its  serial  port.  The con‐

nection to the computer is via ethernet.  So there are two adâdi‐
tional  devices  between the station and the computer  that  will
be  destroyed  before  the  computer  gets hit: the device server
(with its own power supply and ground) and a small  ethernet  hub
(costs only 40$).

t  really want to pay for more repairs of the
Of  course,  I  donâconsole, so I added a surge  protector   cir‐
cuit   from   Meteolabor  (www.meteolabor.ch).    They build very
fine devices and have vast experience  with  lightning  and  NEMP

protection  (they  also  do miliâtary  projects  for NEMP protec‐
tion).  If this setup survives the storm season in autumn, we can
say "problem solved!".

10 to a Vantage Pro
âââââââââââââââââââââââââââââââââââââââââââââââ
Connecting  the Lantronix UDSââ The Vantage Pro comes with a con‐
pin
nector  suitable  for  the  9âCOM1/2  serial  ports   on   a  PC.
10 has a 25pin old style
The  UDSâconnector.  Both are really overkill, as the Vantage Pro
only uses ground  and  TxD  and  RxD.   To  connect  the  Vantage
10, you must use a nullâmodem connector, i.e. the RxD and TxD
10 behaves like a PC as far as
Pro  to the UDSâlines  must  be  crossed  (the UDSâwiring is con‐
cerned, you could directly connect a modem).

toâDB25 connector  as
If you only have a gender changer and a DB9âI  had  when  I   in‐
stalled   the  Bosco/Gurin station, you may help yourself by cut‐
ting the cable and reconnecting. Here is  how  you have  to  con‐
nect the wires:

ââââââââââââââââ  red
        red  â
âââââââoââââââââ  yellow
      green  â
âââââââoââââââââ  green
     yellow   â There  is  no  need to connect the black wire, it

seems to be unâused.

10
âââââââââââââââââââââââââââââââ
t need any special softare installed on your system,  evâ
Configuring the Lantronix UDSââ You donâerything you need  are  a
few standard utilities installed with any reasonable Unix system.

10âs documentation to learn how to set the IP
Please read the UDSâaddress  and  netmask  parameters.   As  soon
as  you  have a working network configuration, you can connect to
10
port 9999 on the UDSâand get the configuration dialog.  The  fol‐
lowing settings work for me:

    *** basic parameters
    Hardware: Ethernet Autodetect
    IP   addr  192.168.007.003,  gateway  192.168.007.001,netmask
255.255.255.000

    ***************** Channel 1 *****************
    Baudrate 19200, I/F Mode 4C, Flow 00
    Port 10001
ââ none âââ, Port 00000
    Remote IP Adr: â    Connect Mode: C0  Disconn Mode: 00
    Flush   Mode: 00

10 has some clever modes to reduce network  usâ
Note that the UDSâage by grouping several characters in a  single
t  that  great
packet.  While this is great for terminal applications, it really
isnâfor  a  weather  station, where the time when  the  data  ar‐
rives at the computer also plays some role (e.g. for computations
of  rain rate or wind speed), this is why the flush modes are 00.

â
â$Id: uds10.in,v 1.2 2004/03/01 09:44:08 afm Exp $

