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Operation Manual V.34 - Modems, Version 07/97
S1 M2 D1 M5 D2 A/O Da/Te
LOGEM ®
928
Chapter 1
1 Modem Description
The LOGEM ® 928 is a high speed standalone modem for duplex operation
that supports all conventional modulation procedures. The LOGEM ® LGM
28.8D1 has identical features and comes as a rackmounted version while
the LOGEM
® LGH 28.8D1 is the version for top rail installation.
The modems support the operation modes listed below:
• V.34
• V.32bis
• V.32
• V.22bis
• V.22
• V.23dx
• V.21
• V.17, V.29, V.27ter (only for fax operation)
Data transmission is possible with synchronous or asynchronous
procedures. The modems are designed for operation on switched and
leased lines as well. Software configuration is performed using AT, V.25bis
or DNL commands, DIP switches are available for hardware configuration.
As an option an additional board for 2/4 wire leased line operation with
dial backup feature is available thus providing a second line interface.
Data protection protocols acc. to V.42bis and MNP4 are implemented for
the transmission procedures acc. to ITU-T V.34, V.32bis, V.32, V.22bis
and V.21 thus allowing for almost errorless data transmission between to
terminal equipments. Due to the implementation of data compression
methods acc. to V.42bis and MNP5 data transmission rate may increase
up to the factor 4 (max. 115200 bit/s).
Safety aspects are taken into consideration starting with the dial up. At
activated password protection any caller is only put through to the terminal
equipment (i.e.a host) after typing the correct password.
With an additional callback number a connection is terminated after the
correct password has been transfered and the modem dials the callback
number. A connection to a host is only switched when the connection
has been established succcessfully during the callback procedure.
The modems even cooperate with terminal equipment that might not be
able to transfer dial commands. The operation mode “direct call“ allows
for dialing of a predefined calling number just by switching the control
line S1/DTR from OFF to ON.
As a further feature the modems are designed for remote configuration
as direct or local modem configuration is not possible at some
applications, i.e. a terminal is not available or the operation mode of dif-
ferent remote modems has to be altered. The modems from the LOGEM
Modem Description