1 autobauding, Autobauding, Ac75 at command set – Siemens AC75 User Manual
Page 117
AC75 AT Command Set
4.9 AT+IPR
s
AC75_ATC_V01.002
Page 117 of 569
10/30/06
Confidential / Released
19200
28800
38400
57600
115200
230400
460800
Notes
• Delivery value for
is 115200bps on ASC0 and 115200bps on ASC1. It will not be restored with
.
• 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 nevertheless 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
Combining AT commands on the same
.
- 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 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 shall be operated in Multiplex mode we suggest a minimum bit rate of 4800bps.
• 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.
• A selected bit rate takes effect after the write commands returns OK.
• If Java is running, the firmware will ignore any settings made with
. Responses to the read, write or
test command will be invalid or deliver "ERROR". See also "AC75 Java User's Guide"
ing serial interface".
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 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 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 you switch to autobaud mode, then autobauding does not take effect immediately after the write com-
mand
=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
read command which still returns the old
baudrate until the next restart.
Before you activate autobauding switch on the local echo with
1. 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 ech-
oed 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 bit rate of the TE.