Using with Campbell Scientific Dataloggers
If the COM110 modem has definitely been registered on the GSM
network, check that the registration is for ‘non-transparent use’. Also
check it is enabled for GSM Data (CSD) at 9600 baud – not just
GPRS data. For GSM data connections you need to be able to connect
from analogue landlines – the SIM provider will normally give you a
second phone number to dial it on.
or
•
It is not fitted with a SIM, the SIM draw is not in place or the SIM is not
enabled (check with your provider)
or
•
The SIM is programmed to require a PIN to be entered every time it is turned
on.
This is often the case with newly supplied SIMs.
We strongly
recommend that this feature is disabled; this is best done using a GSM phone
(please refer to your SIM provider for more information).
Please refer to Appendix A if you can only access a network where
use of a PIN is a legal obligation with the airtime provider.
•
The power supply is inadequate, e.g. it cannot supply the high surge currents
during transmission. (See Section 6.3.)
Once communication is established with a datalogger via the COM110, it is
essential to monitor how error-free the communications link is, Loggernet
generates log files which indicate the number of attempts required to retrieve good
data (‘retries’). While the chances of getting bad data stored to disk are very small
(because of the error checking protocols used) the speed at which data is collected
can fall markedly if the link is very noisy. This will lead to much higher phone
charges. If many retries are recorded it is worth checking the signal strength,
studying the antenna position and the likely causes of interference.
If you still encounter problems it is also worth checking the firmware version of
the COM110 modem. Campbell Scientific has validated use with units with
firmware revision: “R7.45” (checked using instruction
ATI3
). While later
software revisions will probably be backwards compatible, older software may not
work so well. Please contact your supplier for an upgrade if necessary.
11.2 A GSM Base Station Fails to Get a Response from the
logger
Check the following points:
•
Is the COM110 modem configured to ignore hardware handshaking? – It will
be if setup with the Mobile Data Assistant.
•
Have you ensured that your base station modem setup includes commands to
switch off flow control from the base station?
•
Are you powering the COM110 modem on and off periodically?
•
If so, the datalogger program which is controlling the power of the COM110
modem is either wrong, or is not running (perhaps due to a low battery
voltage).
•
The number you are dialling - is the voice number for the SIM rather than the
data number - if you get "deadline" when the COM110 modem is on or an
"answerphone" service when it is turned off this is almost certainly the
problem.
NOTE
NOTE
31
