Dumb Mode Characteristics

When the modem powers-up or experiences a low level reset, it initiates an automatic connection. The modem also initiates a connection if a previous attempt fails and an S7 timeout occurs.

The S0 register value determines the automatic connection mode, answer or originate. S0 value of 0 indicates originate mode leased-line handshaking. S0 values greater than 0 indicate answer mode leased-line handshaking.

At power-up, the controller automatically checks to see if the modem is configured for leased-line operation. If so, the modem begins handshaking in the answer or originate mode specified by S0.

The following table describes the effect of DTR in Dumb Leased Line mode of operation. The rows present the possible operating modes, and the columns describe events supported by the &D commands.

Operating                                                                               

Mode         			&D0                  &D1                   &D2                    

                                                                                        

Power-up     
				goes off-hook           goes off-hook            Waits for DTR             

             and connects            and connects             going off-to-on           

                                                                                        

                                                                                        

DTR          ignores all             goes on-hook on          Disconnects on            

             changes                 on-to-off                on-to-off                 

                                                                                        

                                                                                        

Lost Carrier Stays off-hook          goes on-hook             goes on-hook              

                                                                                        

                                                                                        

Next Action  Starts handshake        Goes off-hook and        Waits for DTR going       

                                     connects                   off-to-on before         

                                                              off-hook

Timing of DTR Off-To-On Transitions

The off-to-on transition of the DTR lead function may initiate certain functions as described in the following information. The process initiated by the DTR off-to-on transition is started no sooner than 5 ms and no later than 50 ms of the DTR transition. S25 does not affect DTR off-to-on timing under any conditions.

Timing of DTR On-To-Off Transitions

If the modem is online, and a DTR on-to-off transition occurs, it must last at least the time indicated by the value of S25 to be valid; shorter durations are ignored by the modem. Thus, the processes previously mentioned are started no sooner than the time indicated by the S25 register; and no later than 50 ms longer than the time in S25.

DTR-Initiated Hard Reset (&D3 in effect)

If &D3 is in effect, the modem begins a hard reset process within 1 ms of the DTR on-to-off event regardless of the current state of the modem and regardless of the &Qn command in effect. S25 does not affect DTR on-to-off timing when &D3 is in effect.

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