Motorola 326X V.34, and V.32bis, V.34-SDC manual Option Set 3-Sync Dial Only

With this option set, the local and remote modems are configured for SDC operation. The modems default to Fast Call=Lvl3, and use LAPM error correction with modified V.42bis data compression. Enable Option Set 2 in both the local and remote modems, and ensure that Mode (AT*SM) is set the same in both modems.

The modem uses the adaptive rate feature in the V.34 Auto modulation mode. This ensures maximum throughput when line quality is poor.

Option Set 3—Sync Dial Only

Option Set 3 satisfies the needs of a synchronous dial application (see Table 4-2). With Option Set 3, the modem provides the network timing (Clock=Internal). Select a data rate at which the modem communicates with the DTE, using DTE Rate (AT*DE). Consult the description in Appendix A.

With this option set, the local and remote modems are configured for SDC operation. The modems default to Fast Call=Lvl3, and use LAPM error correction with a modified V.42bis data compression. Enable Option Set 3 in both the local and remote modems, and ensure that Mode (AT*SM) is set the same in both modems.

With Option Set 3, DTR=108.1 so that an off-to-on DTR transition instructs the modem to connect to the telephone line. If the modem detects an incoming call, the call is connected. If the modem does not detect an incoming call and Default Dial (AT*DA) is enabled, the modem dials the number specified. If Default Dial is disabled, the modem refers to the Modulation Mode option (AT*MM). If set to Answer, the modem goes off-hook and sends an answer-back tone. An on-to-off DTR transition disconnects the modem from the telephone line. If DTR is low, the modem does not auto-answer. DTR transitions govern how the modem answers and disconnects calls. All options in the ACU OPT’S category are set for a typical synchronous DTE.

The modem uses the adaptive rate feature in the V.34 Auto modulation mode. This ensures maximum throughput when line quality is poor.

Option Set 4—Sync Leased Line with Dial Restoral; No ACU (Models 3261/ 63/66/68)

Option Set 4 uses the modem’s leased line restoral feature. With this option set, the modem operates primarily on a leased line unless that line fails. If so, the modem automatically restores the connection over a single dial line. You must install a 326XFAST-SDC Modem at both ends of the leased line to implement restoral.

Option Set 4 configures the modem for a general restoral application (see Table 4-2). The modem uses the adaptive rate feature in the V.34 Auto modulation mode. This setting ensures maximum throughput when line quality deteriorates. If restoral criteria are met, the modem automatically reroutes data traffic through the public switched telephone network (PSTN) over a single dial line. At that time, the modem attempts to run at 28.8 kbps over the dial line, and falls back to lower speeds if required. After an hour, the modem returns to the leased line.

With Option Set 4, the modem provides the network timing (Clock=Internal). Select a data rate at which the modem communicates with the DTE, using DTE Rate (AT*DE). Refer to the description in Appendix A.

Configuring the Modem

Configuring the Modem 4-9