Autobauding - Siemens MC35 Command Set

AT Command Set
Generally, AT+IPR=x should be used as a standalone command. If nevertheless
combinations with other commands on the same line cannot be avoided, there are
several constraints to be considered:
· Avoid combinations with the AT commands listed in Chapter 1.4.2.
· 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 com-
mands 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 com-
mands will be correctly sent at the new bit rate.

2.45.1 Autobauding

Autobauding allows the GSM engine to automatically detect the bitrate configured in the host applica-
tion. 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 synchro-
nization, 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 syn-
chronized 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 auto-
baud 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 2.45.
· See also AT+ILRR Set TE-TA local rate reporting , pg. 45
Autobauding and multiplex mode
If autobauding is active you cannot switch to multiplex mode (see +CMUX, pg. 101). Vice versa, when
you run the multiplex mode, the write command AT+IPR=<rate> cannot be used.
MC35_ATC_01_V05.00 Page 48 of 256 15.07.2002