S-Register Definitions

S0

Rings to Auto-Answer. Sets the number of rings required before the Digi device automatically answers a call. Setting this register to Zero disables auto-answer mode.

0-255

Rings

S1

Ring Counter. Specifies the current number of rings. S1 is incremented each time the modem detects a ring signal on the telephone line. S1 is cleared when the existing connection is established or dropped.

0-255

Rings

S2

Escape Character. S2 holds the value of the ASCII character used as the escape character. The default value corresponds to an ASCII '+'. A value over 127 disables the escape process. That is, no escape character will be recognized.

0-255

ASCII

S3

Carriage Return Character. Sets the value of the carriage return character used when displaying commands or results.

0-127

ASCII

S4

Line Feed Character. Sets the character recognized as a line feed when displaying commands or results. If verbose result codes are used, the Line Feed control character is output after the Carriage Return control character.

0-127

ASCII

S5

Backspace Character. Sets the character recognized as a backspace, used to erase the last character typed on the command line.

0-32

ASCII

S12

Escape Prompt Delay. The amount of time required before and after an escape sequence (+++) is entered in order for the modem to transition from data mode to command mode.

0-255

0.02 second, 20 ms

S14

General Options Status. Indicates the status of command options.

• Default: 138 (8Ah) (10001010b)
• Bit 0: Ignored.
• Bit 1: Command echo (En):

0 = Disabled (E0).

1 = Enabled (E1). (Default.)

• Bits 2 and 4: Quiet mode (An):

0 = Display result codes (Q0). (Default.)

1 = Do not display result codes (Q1).

2 = Disables “CONNECT” result codes (Q2).

3 = Disables “CONNECT” result codes on incoming
connections (Q3).

• Bit 3: Result codes (Vn):

0 = Display numeric result codes (V0).

1 = Display verbose result codes (V1). (Default.)

• Bits 5-7: Ignored.

S21

General Options Status. Indicates the status of command options.

• Default: 52 (34h) (00110100b)
• Bits 0 - 2: Ignored.
• Bits 3-4: The DTE’s DTR behavior (&Dn):

0 = DTR drop is ignored (&D0).

1 = DTR drop causes a transition from data to command mode without hanging up an existing connection (&D1).

2 = DTR drop hangs up the existing connection (&D2) (Default.)

3 = DTR drop causes the modem to do a soft reset if the ATZ command was executed (&D3).

• Bit 5: Modem’s DTR behavior:

0 = The modem’s DTR remains on at all times (&C0).

1 = The modem’s DTR follows the state of the TCP connection (&C1). (Default.)

• Bits 6-7: Ignored.

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