Siemens SIMATIC S7-300 Manual page 34

5 Commissioning of the Application
5.1 General preparations
Step
3.
4.
.
Note
The modem is only accessed by AT commands when it is in the command
phase. If this is not the case, the modem must be reset to factory settings.
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Select the respective COM interface.
Set character format and baud rate to the same values as the serial interface of
the MD720-3.
The factory settings of the MD720-3 are as follows:
Baud rate: 19200 bps
Character format: 8N1.
The baud rate is changed via AT command: AT+IPR=<baud rate>. Enter this
command in the terminal program and press the return key.
Procedure
Sending and Receiving SMS Messages with MD720-3
V 2.1, ID Number: 25545680