ZyXEL Communications Omni TA128 - Manual (Page 59)

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ATB19 56000bps
There are two modes of synchronous operation:
1. Asynchronous commands, synchronous data (AT&M1):
The TA128 accepts AT commands in asynchronous mode.
Once the call is connected, it enters synchronous mode for data
transmission.
2. Synchronous mode (AT&M3*I1): The TA128 accepts
synchronous commands from V.25 bis or a PC with an add-on
synchronous card, and exchanges data synchronously with a
remote TA.
O O Note: The TA128 does not support network independent clock
compensation. The synchronous timing source must be supplied
by the TA128 , which is phase locked to the network
synchronous clock.
When in V.25bis command mode, the TA128 supports the bit-
oriented HDLC (High-Level Link Control) synchronous protocol
which most synchronous communication links use. Use AT*Ii to
enable V.25bis commands. For synchronous applications the TA is
set for use with one application, in normal situations. Save the
desired settings in the power-on profile and the TA will start up in
synchronous mode with V.25bis enabled. A special command set
RST is provided to get the TA back to asynchronous AT command
mode from V.25bis mode.
When the TA is used as a DCE device with a router or main-frame
system, use the following command string for best results:
AT&S1&M3*I1&W0Z0
V.25bis Command Set
Command Messages
CRN
Dial command with number provided.