> 4.9.1 | Autobauding

> 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 bitrate used by the TE is detected by the TA. To allow the bitrate to be synchronized simply use an "AT" or "at" string. This is necessary when you start up the ME 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.

> • | Restrictions on autobauding operation:

> - | If autobaud mode is enabled, then autobauding does not take effect immediately after the write command AT+IPR=0 ends. Instead the old bitrate remains active. The autobaud mode is activated with the next restart of the TA. This is indicated by any following AT+IPR read command which still returns the old bitrate until the next restart. Before you activate autobauding switch on the local echo with ATE1. To verify if autobauding has become effective after restart first send only the characters "AT" or "at" and check that they are echoed within 100ms. In some cases you may need to repeat this several times, until both characters are properly echoed within 100ms. Please note that after the successful synchronization between TE and TA the autobauding mechanism of the TA is deactivated until next restart. So, while autobauding is enabled you will need to restart the TA each time after changing the bitrate of the TE.

> - | The TA cannot distinguish between 1 and 2 stop bits. Therefore, 1 stop bit will be used by the TA.

> - | The command A/ cannot be used.

> - | Only the first "AT" or "at" after restart of the module can be detected (neither "At" nor "aT"). This means that all the AT commands have to use the same bitrate and frame type.

> - | The second serial interface ASC1 does not support autobauding.

> - | Autobauding cannot be used if the ME operates with Java.

> - | URCs that may be issued before the ME detects a new bitrate (by receiving the first AT character) will be sent at the previously detected bitrate or, after ME restart, at 115200 bps.

> • | Autobauding and bitrate after restart: Unless the bitrate is determined, the following constraints apply:

> - | An incoming CSD call or a network initiated GPRS request cannot be accepted. This must be taken into account when autobauding and autoanswer mode (ATS0 ≠ 0) are enabled at the same time, escpecially if SIM PIN 1 authentication is done automatically and the setting ATS0 ≠ 0 is stored to the user profile with AT&W.

> - | Until the bitrate is found, URCs generated after restart will be output at 115200 bps. This applies only to user defined URCs, such as "+CREG", "CCWA", "^SCKS" etc. The URCs "^SYSSTART", "^SYSSTART CHARGE-ONLY MODE" and "^SYSSTART AIRPLANE MODE" will not be indicated when autobauding is enabled.

> Note: To avoid any problems caused by undetermined bitrates in the direction from TA to TE we strongly recommend to configure a fixed bitrate rather than autobauding.

> • | Autobauding and multiplex mode: If autobauding is active you cannot switch to multiplex mode (see AT+CMUX).