Maxim Integrated 73M2901CE AT Command - Manual (Page 29)

UG_2901CE_027 73M2901CE AT Command User Guide
Rev. 2.0 29
4.4.25 S24 – Desired DCE Speed
(Default = 0)
0 = Last AT Command Speed
3 = 300 bits/s
5 = 1200 bits/s
6 = 2400 bits/s
Note: This command only pertains to the DCE speed, and not to Bell or ITU operation. To establish ITU
or Bell connections, use S24 combined with the B command or set S26 bit 7 to obtain the desired modem
operation.
4.4.26 S25 – Protocol Selection Register
(Default = 0)
Register S25 reflects the status of certain options. Default Value is 0. Register S25 is a bit mapped
register whose bits are defined as follows:
Bit 0 1 = Disconnect if No Protocol is detected
Bit 1 1 = LAP-M Protocol
Note: In order to perform a connection without protocol negotiation, clear all bits (set to 0).
When a connection is made and the selected protocol is detected an appropriate result code is returned:
PROTOCOL: NONE or numeric ‘70’
PROTOCOL: LAPM or numeric ‘77’
If no protocol is detected within 1.5 seconds after CARRIER is established, PROTOCOL: NONE or
numeric result code ‘70’ will be sent.
4.4.27 S26 – Bit Mapped Data Mode Control Register
(Default = 0)
Register S26 reflects the status of certain options. Register S26 is a bit mapped register whose bits are
defined as follows:
Bit 0
1 = Force rate change to 1200 bps.
Bit 1 0 = Disables speed negotiation during a retrain request (default).
1 = Enables speed negotiation during a retrain request.
Bit 2 0 = Disables automatic retrain requests (default).
1 = Enables an automatic retrain request to be negotiated.
Bit 3 0 = Disables retrain request response (default).
1 = Enables the modem to respond to a retrain request.
Bit 4 0 = Select 1800 Hz guard tone to be generated during answer mode handshake (default).
1 = Select 550 Hz guard tone to be generated during answer mode handshake (not used in North
America).