Using with Campbell Scientific Dataloggers
25
modem initialisation string sets the timeout at 45 seconds and Loggernet will
increase its own timeouts to suit. Normally you are allowed to increase this setting
up to 60 (seconds) if a call is seen to take such a long time to connect. Setting too
long a delay may, however, slow down the retry sequence in the event of a failed
connection.
To add this setting, use the Phone modem option in Loggernet where you can edit
the modem initialisation string in the setup screen. You cannot amend this setting
for a TAPI interface in a way that Loggernet can also detect.
Campbell Scientific communications software includes other time-outs which are
used to check for hung communications links. These are set to be quite short for
land-based modems, as the response to any command sent from the PC should be
almost instantaneous. A link to a remote COM110A modem normally passes
through several nodes of a digital data network, all of which can add delays.
Usually these delays are less than one second and so have no effect on the
communications process. However, on a long distance call or busy network, the
built in time-out delay for the PC software may need to be extended.
In Loggernet or PC400W, a station-specific delay can be added by increasing the
time in the ‘Extra response time’ box shown on the datalogger hardware set-up
screen. This delay is entered in seconds. Loggernet has a default, built-in, delay of
~2 seconds, which is adequate for use with the COM110A modem in most cases.
On busy networks, or with poor communication links, a value of 3 or even 4 may
be required, to allow the error correction process to function.
Where a COM110A modem is used as the base station modem, it is advisable to
increase these delays even more by perhaps another 1-2 seconds, if
communications are proving to be unreliable.
Entering too large a delay can slow down the entire communications
process, and so an optimal value should be determined by trial and
error.
9. Using Loggernet for GPRS communications
9.1 Setting up to call a logger with a fixed IP address
Where there are no restrictions on outgoing connections from Loggernet to the
remote IP address, the connection can be setup as a standard IPPort connection as
documented in the help system. An example is shown below. The only change
from entering the IP address and port in the normal way is the an “Extra response”
delay of a few seconds may be required when using a slow connection.
Do not extend the extra response beyond 5 secs as it is not
beneficial.
NOTE
NOTE
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