User guide

User Guide
11
By implication the logger defaults to the PPPOpen state as soon a
port is activated for PPP. This is not dependent on a program
running, although if you load a program that incorrectly calls
PPPClose you could block further communications.
Where power and data costs have to be kept to an absolute minimum other
approaches can be adopted, these are where the logger opens the connection and
then sends data back to the PC (or even another datalogger) using the Senddata
command, prior to shutting the port and closing down the PPP connection.
Alternatively you can use the “call-back” function of Loggernet (see call-back
under the CRBasic help) to make a special call back to the logger (using the
Sendvariables command) which in turn triggers a normal data collection from the
logger. Once completed the TCP port and PPP connection can be shut down.
Please contact CS for more details on these options.
7.6 Calling the logger in GSM data mode
In some circumstances it may be advantageous to call out to the system in GSM
Data mode by dialling and connecting with a phone modem. This may be
necessary in the event of failure of the GPRS network or network connections that
prevent dial-back to the Loggernet server. It is possible to call the logger in the
standard way (refer to the CS-GSM manual) providing you know the GSM data
phone number and also providing the logger has periods of operation when the
PPP connection is not enabled, i.e. PPPClose has been called.
It is not possible to establish a GSM data connection whilst a PPP
session is in progress.
8. Fault finding
There is no direct feedback provided by the datalogger of the state of the PPP
connection, e.g. an LED indicator. There are some 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 datalogger (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 and connect to the
datalogger and bring up the TCP/IP screen. If the modem is using the DHCP
protocol to establish your IP address and gateway (most will) then you will only
see non-zero ppp ip: and ppp gw: values appear in the TCP/IP Info window once
the logger has connected to the network and has been told which values to use.
Note, that even if you are assigned a public IP address, the IP the network
assigned to you may be not the same (and be private), as usually the public IP is
directed to your private IP by an external router. The screen below shows typical
settings once the connection is up and running:
NOTE
NOTE