S10 - Lost Carrier Hang Up Delay

Type
value (deciseconds)

Value range
1 to 255, Default value: 14

Stored by &Wn yes

Displayed by &V yes

Description
The time specified in S10 is the length of time (in deciseconds) that a carrier may remain undetected, in the online state, before the modem starts the hang-up process. If carrier is lost and its return is not reported by the bit pump for a time equal to the difference in times indicated by the values of S9 and S10, then the modem starts the hang-up process. If carrier returns before the time limit, the carrier must last for the S9 time before the modem considers carrier to be on.

If S10 is set to 255, the modem does not hang up when carrier is lost (and the modem continues to send its modulated carrier). The modem may attempt a retrain, but may not hang-up.

See Carrier Detection.

If S10=255 the modem ignores a received protocol disconnect frame (e.g., a V.42 protocol disconnect). With S10=255, the host system decides when a modem may hang up rather than the modem hanging up on protocol disconnect or loss of carrier.

If the call has been disconnected and there is no carrier, then the escape sequence followed by ATH or turning off DTR (when &D2 or &D3 is selected) will cause the modem to hang up.

The following information describes the behavior of the S10 register when set to a value of 255:

Situation                Behavior                                                                  

Carrier is lost.         The modem turns off the CD lamp (and RLSD lead) but cannot hang up. If    

                         automatic retrain is enabled, the modem tries to retrain, over and over. If 

                         the DTE sends the escape sequence and the ATH command, the modem hangs up  

                         and returns OK.  If carrier returns and a retrain attempt is successful,   

                         the call is re-established.                                                


A protocol disconnect    The modem turns off CD lamp (and RLSD lead) but cannot hang up. If        

message is received,and  automatic retrain is enabled, the modem tries to retrain, over and over. If 

carrier is lost.         the DTE sends the escape sequence and the ATH command, the modem hangs up  

                         and returns OK. If carrier returns and a retrain attempt is successful, the 

                         call is re-established.

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