ZyXEL Communications ACCESSING INTERNET & INTRANET omni series - Manual (Page 65)

V.110 and Synchronous Mode Communications 53
There are two modes of synchronous operation:
1. Asynchronous commands, synchronous data (AT&M1): The
omni 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 omni 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 Note: The omni does not support network independent clock
compensation. The synchronous timing source must be supplied
by the omni , which is phase locked to the network synchronous
clock.
When in V.25bis command mode, the omni 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.
CRSn Dial command with number from memory,
0<=n<=39; n is the memory location.
PRNn; Saves to address n (0<=n<=39).
CIC Receive incoming calls.
DIC Reject incoming calls.