Using with Campbell Scientific Dataloggers
minutes or set up another process, e.g. low frequency pinging, to prevent the
datalogger resetting the connection.
It should be noted that when you download a program to the datalogger via a
TCP/IP connection, and the logger is using its own TCP/IP stack, it will reset the
connection as part of the process of compiling the program. This will cause it to
drop the PPP connection for some tens of seconds. This process should not be
evident from a user standpoint as Loggernet should wait long enough for this to
take place so should not report an error in most instances.
9.2.4 Firewall Issues
When using any of the above call-back methods you need to have the Loggernet
PC either be directly attached to the internet with its own public IP, or be behind a
router that forwards incoming calls to specific ports onto the Loggernet PC. With
some airtime providers you might also be able to setup a private network
connection (or VPN) to the Loggernet PC to avoid it being on the public network.
In addition to allow incoming connections to that PC you will need to open up
“holes” in any firewall software running on the PC and/or external routers to allow
incoming connections to the call-back sockets and outgoing responses from those
sockets.
If using a PC running Windows XP with SP2/SP3, Vista, Windows 7 or Windows
8 (or equivalent server versions) as the Loggernet server you will as a minimum
need to check the Firewall settings, via the advanced setting, and add Exception
rules for the incoming port numbers you wish to allow dataloggers to call back in
on.
You can test the firewall settings by using that PC from outside your local network
to make a connection to Loggernet using the Telnet program (this is an optional
part of recent Windows installations that you may need to enable first). If enabled
use Start, Run, cmd <enter> and then type
telnet n.n.n.n port <enter>
Where n.n.n.n is the public IP address of the LN server and port is the callback
port defined in your IPPort or PakbusTCPServer. When you run this a black
telnet window should appear on the screen and say connected in the top bar. You
should also see messages in Loggernet’s logfile indicating something has
connected to LN on a particular socket (which it is listening on). It will eventually
timeout (as you cannot emulate logger speak). If the telnet box flashes on the
screen or generates an error message in the top bar it is likely one or more of the
firewall, router or Loggernet are setup incorrectly.
If you are unable to install your Loggernet server outside a firewall
or getting routing enabled through the firewall it is possible to use
an NL200 device (installed outside the firewall) to route traffic to a
Loggernet server. Please contact Campbell Scientific for more
details.
10. Preventing COM110 modem Connection Problems
The COM110 differs from previous modems offered by Campbell Scientific in
that it continuously monitors its connection state to the network. The modem will
reset itself if it loses connection which will often re-establish its connection to the
network. Generally, this will provide a reliable connection long term. However,
there is a very small chance that the COM110 modem could crash as a result of
NOTE
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