S154 - Force Port Speed

Command Line Format:
AT [cmds] S154=<value> [cmds] <CR>

Values
0,1 Default value: 0

Stored by &Wn
yes

Displayed by &V
no

Description
The bits in this register enable certain modem behavior for cellular channels.

References
&Fn command (new command to set cellular parameter values).

Description
There are applications in which the DTE needs to operate its port at the line speed even though the modem is buffering characters to and from the DTE. The application provides its own error correction. You may configure the modem to provide this function by the commands W2 and S154=1.

0 The normal relationship of modem port speed to direct and buffered interface modes.
1 The modem shall always change its port speed to match the speed reported by the CONNECT XXXX result code after the result code is sent to the DTE.

Summary of Speed Rules:
After the handshake, the CONNECT XXXX speed:

1 XXXX matches the line speed if the connection uses the direct mode OR if W2 is selected OR if the value of bit 0 of S95 is 1.

2 XXXX matches the last AT speed if a buffered mode is used AND W2 is not selected AND the value of bit 0 of S95 is 0.

After a CONNECT result code:

1 The DTE speed is changed to match the line speed if the value of S154 is 1 OR if the connection uses the direct interface mode (&Q0).

2 The DTE speed is left at the last AT speed if the connection uses a buffered interface mode (e.g. V.42) AND the value of S154 is 0.

Note: The response speed matches the DTE speed after any change in DTE speed, except after a reset or (possibly) after a connection is cleared.

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