Black Box MD885C-R2 Modem User Manual


 
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4.0 General Operation and Special Features
Changing the Operating Mode Fallback parameter to 1 has the following
effects:
• The Modem is configured for V.22 bis 2400 bps/V.22 1200 and 600
bps/V.21 300 bps/V.23 1200/75 bps fallback operation. As a result,
600 and 1200/75 bps appear as additional selections on the SPEED
LIMIT LCD screens.
• Fallback to V.22 bis Bell 212A and Bell 103 compatibility is disabled.
• An AT command is available (in Hayes mode only) that allows control
over operating mode as follows: F0—Multi-mode operation (default);
F1—V.21, 300 bps; F2—V.22, 600 bps; F3—V.23, 1200/75 bps; F4—V.22,
1200 bps; F5—V.22 bis, 2400 bps; F6—V.32 (highest common speed).
Except for multi-mode operation, the mode and speed are limited to the
mode and speed specified. Multi-mode operation allows the modem to
automatically fall back to the most efficient mode that can be used by
both modems.
The preferred mode is V.32 (9600 or 4800 bps, asynchronous/ synchronous,
full duplex); however, if the other modem does not support the V.32
standard, the Modem falls back to one of the modes listed below. The fallback
modes are listed in the order in which they are attempted by the Modem in
normal operation.
Table 4-5. V.22 bis/BELL 212A/BELL 103 FALLBACK (DEFAULT).
MODE DESCRIPTION
V.22 bis 2400 bps asynchronous/synchronous
Bell 212A 1200 bps asynchronous/synchronous
Bell 103 0-300 bps asynchronous
All modes are full duplex.
If V.22 bis/V.22/V.21/V.23 fallback operation is enabled, the following
fallback modes are available. As in the previous list, the modes are listed
in the order in which they are attempted by the Modem.