Campbell Scientific PC208 Datalogger Support Software - Manual (Page 111)

APPENDIX A. APPLICATIONS NOTES ON INTERFACE DEVICES
A-3
A.3 MODEM INITIALIZATION FILE
High speed modems and fax modems have a
larger command set and are more complex
than the old 1200 baud modems. Unfortunately
to make them downward compatible with the
1200 baud modems, additional commands are
required.
PC208E, GraphTerm, and Telcom uses a
modem initialization file “MODEM.INI” to
configure the telephone modem to work with
PC208. This file is installed in the directory in
which GT or Telcom was installed. The install
program will not overwrite an existing
“MODEM.INI” file. Within this file, there is a list
of different modems and their initialization
strings to help you configure your modem to
work with PC208. The list was created from
customer feedback and some in-house testing,
and offers no guarantee that all the modem
information is universally correct.
The first three lines of the “MODEM.INI” file are
used by GT and Telcom. Following is a copy of
the first three lines of the file containing the
default strings for a 1200 baud modem:
ATZ
ATE1QV
If, for example, your modem was a “Dell Internal
Modem”, you would replace the above with the
following:
AT&F
AT&C1&D2&Q0&K0V0
Please note that the third line in both of these
cases is a blank line. Everything below these
first three lines is modem information only. You
can use a text editor such as MS-DOS Edit to
view and edit this file. If you see your modem
listed, you need to replace the default strings at
the top of the file with the ones for your modem.
This can be done by either retyping it or by
using the cut and paste option within your text
editor.
A.3.1. FILE DEFINITION
The first line is for the modem reset string.
PC208 uses this to reset the modem to a known
state. Line two is the initialization string, which
is used to configure the modem to work with
PC208. The third line is for a dialing string such
as calling card phone numbers and access
codes. This line is sent before the information
in the station file phone number field. The
station file phone number is appended to the
end of this string.
The first three lines of the file must exist. If a
reset is not needed, this line can be left blank.
The same applies to the other two lines in the
file. A blank line must exist for each line which
has been omitted.
By default, the “MODEM.INI” file is installed in
the directory specified in the install program.
PC208 looks for this file in three different
places. The first place it looks is in the current
working directory. Next it looks in the directory
where the station file is located. The last place
it looks for the file is the directory in which
PC208 is located. PC208 uses the first
“MODEM.INI” file it finds in the order described
above. This allows for use of multiple
“MODEM.INI” files for special applications.
A.3.2 MODEM COMMANDS
Modem commands differ from one brand to
another and even between the different models
from the same manufacture. If your modem is
not listed, use the following information and
your modem’s manual to determine the
appropriate initialization strings. Find the
section in the modem’s manual that explains
the AT and extended AT commands.
Line 1 of the “MODEM.INI” file.
1. Find the command which returns your
modem to factory defaults. In most
modems the command is &F.
Line 2 of the “MODEM.INI” file.
1. Find the command which disables the local
flow control. This is the flow control
between the modem and the computer
sometimes called the DTE and DCE flow
control. &K0 is one of the commands
commonly used to disable local flow control.