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TC63_ATC_V00.490

Page 101 of 501

5/24/05

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• Factory default is autobauding enabled (

=0) on ASC0 and 57600bps on ASC1. It will not be restored

• The current setting of 

 will be preserved when you download firmware (i.e. a firmware update does

not restore the factory setting) or in the event of power failure. 

• Generally, 

 should be used as a standalone command. If nethertheless combinations with other com-

mands on the same command line cannot be avoided, there are several constraints to be considered: 
- Avoid combinations with the AT commands listed in Section 

- Take into account, that a delay of 100ms is required between the response to the last command (e.g. OK)

and the next command on the same line.

- When you enter 

=0, autobauding will be activated after the response to the last command is

received.

- When local echo is active (

1) and you enter 

=x with other commands you may encounter the

following problem: if switching to the new bit rate takes effect while a response is being transmitted, the

last bytes may be sent with the new bit rate and thus, not properly transmitted. The following commands

will be correctly sent at the new bit rate.

• In order to account for greater amounts of data it is recommended to choose a minimum bit rate of 2400 bps.

If the ME is operated in Multiplex mode we suggest a minimum bit rate of 4800bps. 

• A selected bit rate takes effect after the write commands returns OK (except for Multiplex mode). 
• In Multiplex mode, the write command 

 will not change the bit rate currently used, but the

new bit rate will be stored and becomes active, when the module is restarted. 

To take advantage of autobaud mode specific attention must be paid to the following requirements: 
• Synchronization between TE and TA

Ensure that TE and TA are correctly synchronized and the bit rate used by the TE is detected by the TA. To

allow the bit rate to be synchronized simply use an "AT" or "at" string. This is necessary 
- after you have activated autobauding
- when you start up the GSM engine while autobauding is enabled. It is recommended to wait 3 to 5 seconds

before sending the first AT character. Otherwise undefined characters might be returned.

If you want to use autobauding and autoanswer at the same time, you can easily enable the TE-TA synchro-

nization, when you activate autobauding first and then configure the autoanswer mode (

≠ 0).

• Restrictions on autobauding operation

- The serial interface shall be used with 8 data bits, no parity and 1 stop bit (factory setting), e.g. 2 stop bits

are not supported for autobaud mode. 

- The command 

 cannot be used.

- Only the strings "AT" or "at" can be detected (neither "At" nor "aT").
- URCs that may be issued before the ME detects a new bit rate (by receiving the first AT character) will be