Motorola 326X V.34 - Manual (Page 69)

Configuring the Modem 4-7
Confi
guring
the Modem
Option Set Descriptions—326X V.32bis and V.34 Modems
Option Set 1—Async Calls to Central Site Using the AT ACU
With Option Set 1, the modem communicates over dial lines using an asynchronous
data format. This option set is appropriate for home or office use where you plan to
dial, for example, into a central-site computer, minicomputer, an electronic bulletin
board, or a personal computer. When you first install the modem, it is set to power up
with Option Set 1 as the factory default. The modem recognizes the standard AT
Command Set and the Motorola-enhanced AT Command set.
To satisfy common asynchronous communications software packages, Option Set 1
holds several EIA 232-D (ITU V.24) control signals asserted (see Tables 4-1 and
4-2). The modem originates calls and answers incoming calls according to the setting
of S-Register 0 (see the “S-Registers” section in Chapter 5 for more information).
At the beginning of each connection, the modem negotiates the highest common data
rate with the remote modem set to its factory default setting or automode. The
modem also uses the adaptive rate feature in the V.34, V.32bis, or V.32 modulation
modes. This ensures maximum throughput when line quality is poor.
Option Set 2—Sync Answering Central Site Without an ACU
Option Set 2 satisfies the needs of a synchronous application where most calls are to
a central site (see Table 4-1).
Because calls are received primarily at the central site, the modem is set to answer
calls automatically. With DTR=108.2, the local DTE can control the DTR signal.
This allows the local DTE to use DTR transitions to connect the modem to the
central site at the beginning of transmission and disconnect it when transmission
ends.
At the beginning of each connection, the modem negotiates the highest common data
rate with the remote modem. The modem uses the adaptive rate feature in the V.34,
V.32bis, or V.32 modulation modes. This ensures maximum throughput when line
quality is poor.
Option Set 3—Sync Calls to Central Site Using the V.25bis ACU
Option Set 3 satisfies the needs of a synchronous application, where the remote
modems originate calls to a central site (see Table 4-1).
With Option Set 3, the modem originates calls with its V.25bis ACU. The DTR
option is set to 108.2 so that the V.25bis ACU can manipulate the DTR signal. All
other options in the ACU OPT’S category are set for a typical synchronous DTE.
At the beginning of each connection, the modem negotiates the highest common data
rate with the remote modem. The modem uses the adaptive rate feature in the V.34,
V.32bis, or V.32 modulation modes. This ensures maximum throughput when line
quality is poor.