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COMSPHERE 3900 Series Modems
Async/Sync Mode: Sync
Nxt Sync Async
Asynchronous/Synchronous Mode. Determines whether the modem operates in Asynchronous mode or
Synchronous mode. If the AT command set is enabled and this configuration option is set to Sync, then
the modem operates in Async mode when offline.
For Async Dial, Async Leased and UNIX Dial, Async is the factory default.
The AT commands for Async Mode are &M0 or &Q0.
The AT commands for Sync Mode are &M1, &M2, &M3, or &Q1, &Q2, &Q3.
Async DTE Rate: 19200
Nxt 19200 57600 38400 14400 12000 9600 7200 4800 2400 1200 0–300
This configuration option only appears if Async/Sync Mode is configured for Async.
Asynchronous DTE Data Rate. Identifies the asynchronous DTE's operating rate to the modem. Data rates
from 57,600 bps to 300 bps are supported.
NOTE: To prevent losing data in 57,600 bps applications, a 16650 UART on the PC's serial port is
required, as well as a communications package which can take advantage of its 16-byte buffer. In
addition, a 386 PC (25 MHz or faster) is required, and the RS232 cable length must be minimized
to reduce capacitance.
NOTE: To configure the Async DTE Rate different than the modem rate, ensure that the Error Control
Mode configuration option (see the V.42/MNP/Buffer section) is set to BufferMode.
The AT prefix determines Async DTE Rate.
Asyn #Data Bits: 8
Nxt 8 7 9(DirectMde) 6(DirectMde)
This configuration option only appears if Async/Sync Mode is configured for Async.
Asynchronous Number of Data Bits. Determines if the asynchronous data length is composed of 6, 7, 8, or
9 data bits. This data length excludes start, parity, and stop bits.
H 8
Sets data length to 8 data bits.
H 7
Sets data length to 7 data bits.
H 9(DirectMode)
Sets data length to 9 data bits. Only valid when Error Control configuration option is set to Direct
Mode.
H 6(DirectMode)
Sets data length to 6 data bits. Only valid when Error Control configuration option is set to Direct
Mode.
NOTE: If the DTE Dialer Type configuration option is set to AT or V.25bis Async, then the total character
size must equal 10 bits. Total character size consists of start, data, parity, and stop bits. V.25bis
Async must use 7 data bits with even parity and 1 stop bit. The total character size for Error Control
mode, Direct mode, or Buffer mode must be 11 bits or less.
The AT prefix determines the async character length.
5-10
Table 5-1
(1 of 10)
DTE Interface Configuration Options
September 1998
3910-A2-GN32-40
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