CS-3G Digital Transceiver Kits (including the COM111 modem)
36
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 5.3).
Once communication is established with a data logger via the COM111, 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 COM111 modem. Campbell Scientific has validated use with units
with firmware revision: “R7.53” (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 The modem cannot be configured using the Mobile Data
Assistant package
If the modem does not appear to be correctly responding to commands when
running the Mobile Data Assistant package, aside from checking the cables
and power supply, please make sure that the modem has a valid SIM card
installed in it and if not power cycle the modem again after putting the card
in. Without a card installed the modem will sometimes only echo commands
and not action them and it will fail some of the configuration steps where the
software makes changes to settings which are stored in the SIM card, not the
modem itself.
11.3 GPRS/3G fault finding
– when using the logger TCP/IP
stack
11.3.1 First stage fault finding
The diagnostics screen of the Mobile Data Assistant package allows you to
check the basic connection of the modem to the network and also to get a
measure of the signal strength the modem is seeing, which is a useful tool for
antenna positioning. The IP address of the modem will normally be shown
as no IP as this relates an IP assigned to the modem when running its own
TCP/IP stack.
There is no external feedback provided by the data logger of the state of the
PPP connection, e.g. an LED indicator (although this could be done if
required by including code in your logger program and an LED to a control
port). There are some other methods of checking if a connection has at least
been established. The simplest of these is to connect a PC to the other spare
serial port on the data logger (USB, CS I/O or RS232 depending on which
interface is used for the modem, and presuming you have a compatible
cable/interface). Run the Device Configuration program screen, connect to
the data logger and Deployment, PPP tab to check the PPP status which is
NOTE