Siemens MC55 AT manual Autobauding

14400

19200

28800

38400

57600

115200

230400

Notes

•Delivery value for <rate> is autobauding enabled (AT+IPR=0) on ASC0 and 57600bps on ASC1. It will not be restored with AT&F.

•The current setting of AT+IPR 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, AT+IPR 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 1.4.2, Combining AT commands on the same command line.

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

-When you enter AT+IPR=0, autobauding will be activated after the response to the last command is received.

-When local echo is active (ATE1) and you enter AT+IPR=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 shall be operated in Multiplex mode we suggest a minimum bit rate of 4800bps.

•In Multiplex mode, the write command AT+IPR=<rate> will not change the bit rate currently used, but the new bit rate will be stored and becomes active, when the module is restarted.

•A selected bit rate takes effect after the write commands returns OK.

4.7.1Autobauding

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 (ATS0 ≠ 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 A/ 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 sent at the previously detected bit rate or, after ME restart, at 57600 bps.

MC55_ATC_V04.00	Page 93 of 475	3/17/06
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