Rockwell RCV144ACx, Command Reference Manual

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AT Command Reference Manual
1048 3-17
&Qn - Sync/Async Mode
This command is an extension of the &M command and is used to control the connection modes permitted. It is used in
conjunction with S36 and S48. (Also, see \N.)
NOTE: When the &Q0 to &Q4 command is issued to select the mode, the subsequent connect message will report the DCE
speed regardless of the W command and S95 settings.
&Q0 Selects direct asynchronous operation. The value 000b is written to S27 bits 3, 1, and 0,
respectively. See &M0.
&Q1 Selects synchronous connect mode with async off-line command mode. The value 001b is written
to S27 bits 3, 1, and 0, respectively. See &M1. (Serial interface operation only.)
&Q2 Selects synchronous connect mode with async off-line command mode and enables DTR dialing
of directory 0. The value 010b is written to S27 bits 3, 1, and 0, respectively. See &M2. (Serial
interface operation only.)
&Q3 Selects synchronous connect mode with async off-line command mode and enables DTR to act
as Talk/Data switch. The value 011b is written to S27 bits 3, 1, and 0, respectively. See &M3.
(Serial interface operation only.)
&Q4 Selects AutoSync operation. The value 100b is written to S27 bits 3, 1, and 0, respectively.
AutoSync operation, when used in conjunction with the Hayes Synchronous Interface (HSI)
capability in the DTE, provides synchronous communication capability from an asynchronous
terminal.
Starting AutoSync. Set registers S19, S20, and S25 to the desired values before selecting
AutoSync operation with &Q4. After the CONNECT message is issued, the modem waits the
period of time specified by S25 before examining DTR. If DTR is on, the modem enters the
synchronous operating state; if DTR is off, the modem terminates the line connection and returns
to the asynchronous command state.
Stopping AutoSync. AutoSync operation is stopped upon loss of carrier or the on-to-off
transition of DTR. Loss of carrier will cause the modem to return to the asynchronous command
state. An on-to-off transition of DTR will cause the modem to return to the asynchronous
command state and either not terminate the line connection (&D1 active) or terminate the line
connection (any other &Dn command active).
&Q5 The modem will try to negotiate an error-corrected link. The modem can be configured using S36
to determine whether a failure will result in the modem returning on-hook or will result in fallback
to an asynchronous connection. The value 101b is written to S27 bits 3, 1, and 0, respectively.
(Default.)
&Q6 Selects asynchronous operation in normal mode (speed buffering). The value 110b is written to
S27 bits 3, 1, and 0, respectively.
Result Codes:
OK n = 0 to 6.
ERROR Otherwise.