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2. Copy the /usr/share/modems/modem_f.cfg file to a new file with a different name (for example,
modem_fx.cfg).
3. In the new file (modem_fx.cfg), change the line Send "ATE0T\r" to Send "ATcccE0T\r" where ccc is
the added command as specified in your modem manual, as follows:
Change the third line of each of the following stanzas:
v condout
v condin
v ripo
4. Save the changes.
Xon/Xoff modems
Some early modems assume software flow control (Xon/Xoff) between the computer and the modem.
Modems with this design send extra characters during and after the transmitted data. The service
processor cannot accept these extra characters. If your configuration includes such a modem, your
functional results might be unpredictable.
The sample modem configuration files included in this appendix do not support these modems, so custom
configuration files are necessary. Anchor Automation 2400E is an example of such a modem.
If you experience unexplainable performance problems that might be due to Xon/Xoff characters, it is
recommended that you upgrade your modem.
Ring detection
Most modems produce an interrupt request each time they detect a ring signal. Some modems generate
an interrupt only on the first ring signal that they receive. AT&T DataPort 2001 is an example of such a
modem.
The service processor uses the ring interrupt request to count the number of rings when Ring Indicate
Power-On (RIPO) is enabled. If your modem produces an interrupt on only the first ring, set Ring Indicate
Power-On to start on the first ring. Otherwise, you can choose to start Ring Indicate Power-On on any ring
count.
Terminal emulators
The Electronic Service Agent and the service processor are compatible with simple ASCII terminals, and
therefore, are compatible with most emulators. When a remote session is handed off from the service
processor to the operating system, agreement between terminal emulators becomes important.
The NAS Gateway 500's operating system has some built-in terminal emulators. You might also have a
commercially available terminal emulation. It is important that the local and host computers select the
same or compatible terminal emulators so that the key assignments and responses match, ensuring
successful communications and control.
For best formatting, choose line wrap in your terminal emulator setup.
Recovery procedures
Situations such as line noises and power surges can sometimes cause your modem to enter an undefined
state. When it is being used for dial-in, dial-out or ring indicate power-on, your modem is initialized each
time one of these actions is expected. If one of these environmental conditions occurs after your modem
has been initialized, it might be necessary to recover your modem to a known state.
If your modem communicates correctly with remote users, it is probably in control. It might be wise to
occasionally change some of the functional settings and then change them back, just for the sense of
security that the modem is communicating, and to ensure that it has been initialized recently.
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NAS Gateway 500 Service Guide
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