Autobauding - Siemens TC37 Module At Command Reference

AT Command Set
· Take into account that a delay of 100 ms is required between a response to the
last command (e.g. OK) and the next command on the same line.
· 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 at the new bit rate and thus, not properly transmitted. The following
commands will be correctly sent at the new bit rate.

2.46.1 Autobauding

Autobauding allows the GSM engine to automatically detect the bitrate configured in the host
application. The serial interface of the GSM engine supports autobauding for the following bitrates:
1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200. Factory setting is autobauding enabled. This
gives you the flexibility to put the GSM engine into operation no matter what bitrate your host
application is configured to.
To take advantage of autobaud mode specific attention must be paid to the following requirements:
Synchronization between DTE and DCE
Ensure that DTE and DCE are correctly synchronized and the bitrate used by the DTE is detected by
the DCE (= ME). To allow the bitrate to be synchronized simply issue 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
synchronization, when you activate autobauding first and then configure the autoanswer mode
(ATS0=0).
Restrictions on autobauding operation
· The serial interface has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
· The A/ command (and a/) cannot be used.
· Only the strings „AT" or „at" can be detected (neither „aT" nor „At").
· The Unsolicited Result Codes "^SYSSTART", "^SYSSTART ALARM MODE" and "^SYSSTART
CHARGE-ONLY MODE" are not indicated when you start up the ME while autobauding is enabled.
This is due to the fact that the new bitrate is not detected unless DTE and DCE are correctly
synchronized as described above.
· Any other Unsolicited Result Codes that may be issued before the ME detects the new bitrate (by
receiving the first AT command string) will be sent at the previous bitrate.
· It is not recommended to switch to autobauding from a bitrate that cannot be detected by the
autobaud mechnism (e.g. 300 baud). Responses to +IPR=0 and any commands on the same line
might be corrupted.
· When entering several AT commands on the same line, consider the requirements described in the
Notes of Chapter 2.46.
· See also AT+ILRR Set TE-TA local rate reporting , pg. 39
Autobauding and multiplex mode
If autobauding is active you cannot switch to multiplex mode (see +CMUX, pg. 86). Vice versa, when
you run the multiplex mode, the write command AT+IPR=<rate> cannot be used.
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