A-1
Appendix A. Using the TC35T with the
PIN Security Feature Enabled
It is possible to use the TC35T with Campbell Scientific dataloggers with the TC35T’s PIN
(Personal Identification Number) feature enabled. However, this has the following
disadvantages:
•
If the TC35T loses power momentarily, it will not answer further calls until the
datalogger sends the PIN again as part of the normal program sequence. If the
datalogger is programmed to send the PIN only once (leaving the TC35T permanently
switched on), a datalogger reset would be needed to re-enable the system. If a regular
turn on / turn off sequence is used (as described under ‘Controlling the Power
Consumption of the TC35T’), the system will be disabled until the next sequence occurs.
•
If the TC35T fails to unlock the PIN code, for whatever reason, three times in a row, the
SIM card will be permanently locked. This will require you to contact your airtime service
provider to provide an ‘unlock’ code for the SIM.
A.1 Introduction
To operate with the TC35T’s PIN feature enabled, the datalogger must transmit
the command to send the PIN to the TC35T after turning on the power. This is
done using Instruction P97 ‘Initiate Telecommunications’ using the ‘Generic
Modem’ option. This option has only been added in recent releases of the CR510,
CR10X and CR23X operating systems – from versions 1.06, 1.13 and 1.10 (and
later) respectively. If you have one of these dataloggers with an older operating
system, you should contact Campbell Scientific to arrange an upgrade.
Users of other dataloggers, e.g. the 21X, CR10 or CR7, should contact Campbell
Scientific to obtain a copy of a manual written for early versions of the M20T
which describes an alternative, but more complicated, way of sending PIN codes
using special cables and Instruction P98, ‘Send Character’.
Using Instruction P97 with the generic modem option does not require any special
cabling or set-up. It is possible that the generic modem option may not be fully
documented in your datalogger manual, but you should be able to find some
information in the help system of Edlog for Windows (in later releases of
PC208W); if not contact Campbell Scientific. To gain a full understanding of the
general mode of operation of P97 please refer to the examples in the datalogger
manual.
For the purpose of unlocking a PIN code, P97 is used with the datalogger ID set to
0, which causes the instruction simply to send and check the responses to
commands sent to the ‘modem’, without then proceeding to make a call.
A.2 CR10X Program Example
Below is an example program which turns on the TC35T and sends the PIN so
that the TC35T can receive calls.
This program, for the CR10X, shows how to transmit the PIN command
(
AT+CPIN=“nnnnnnn”
, where
nnnnnnn
is the PIN). The program includes a
delay after turning the TC35T on, before calling P97. This is required because it
takes approximately two seconds for the TC35T to power-up.