Using with Campbell Scientific Dataloggers
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You then need to attach a data logger entry to the PakbusTCPServer for each
data logger in your GPRS network, making sure each logger has a unique
Pakbus address which matches the logger Pakbus address set in the logger
using the Device Configuration program. Other settings, such as data
collection parameters, clock correction are set as normal in the data logger
tabs.
8.2.3 Keeping the connection open when calling-back
Once a connection between the logger and the Loggernet PC is established,
if the connection is set to be maintained (Loggernet 4) or always open,
Pakbus messaging will keep the port open and allow Loggernet to make
outgoing calls to the logger, e.g. scheduled data collections. Note, for the
connection to stay open you must set the Pakbus port to be always open (but
do not set this setting if the logger is making less frequent call-back
connections controlled by code in the logger or modem to conserve power).
Whether operating in call-back or fixed IP mode if no valid TCP/IP packets
are received by the data logger within a few minutes, either it or the modem
will test the PPP link locally using a special PPP link test that most providers
support. If that fails or 30 minutes pass with no real data being transferred it
will attempt to hang up the PPP connection and reconnect. This process
allows detection and recovery from a broken GPRS connection (which is not
uncommon on some networks). When using the Modem IP stack the idle
time (no valid data) and maximum time online are settings you can
configure.
In many cases a broken connection may be detected earlier than 30 mins
because for instance Windows detects the loss of the TCP/IP connection
within a few minutes. Please be aware though that these delay can be lengthy
when checking for and debugging lost connections. If you have a poor
connection it is possible to speed up the detection of loss routing back to
Loggernet by adding code to the logger program, e.g. using the PingIP
command. Please contact Campbell Scientific Ltd for further details.
