COMSPHERE 3821Plus Modem

Table 4-1

(8 of 13)

3821Plus AT Commands

&Mn or &Qn ± Async/Sync Mode and DTE Dialer Type

Sets the modem for either asynchronous or synchronous operation and selects the type of dialing method the modem uses.

&M, &M0, &Q, &Q0

Modem operates in Asynchronous mode and uses AT Command protocol.

&M1, &M3, &Q1, &Q3

Modem operates in Synchronous mode and uses AT Command protocol.

&M2, &Q2

Modem operates in Synchronous mode and dials the telephone number stored in directory location 1 when the DTR signal turns Off and then ON.

&M231, &Q231

Modem operates in Asynchronous mode and disables any type of AT command dialing protocol.

&M232, &Q232

Modem operates in Asynchronous mode and uses V.25bis asynchronous dialing.

&M233, &Q233

Modem operates in Synchronous mode and uses V.25bis bisynchronous dialing.

&M234, &Q234

Modem operates in Synchronous mode and uses V.25bis HDLC dialing.

&M235, &Q235 Modem operates in Asynchronous mode and enables a subset of the AT&T command set. This is required for AT&T DATAKIT dial-out applications.

The &M2, &M231 through &M235, &Q2, and Q231 through Q235 commands disable the use of AT commands and force the modem into Dumb mode. The only way to regain control of the modem is to recover AT Commands as described in Recovering AT Commands section in this chapter.

&Rn ± RTS Action

Request-to-Send (RTS) is a signal from the DTE to the modem indicating the DTE has data to send to the modem.

&R, &R0

Standard RS232. DTE controls RTS to the modem in normal EIA-232-D operation. RTS must be

 

ON for the DTE to transmit to the modem.

&R1

 

Ignores RTS. Modem assumes RTS is always ON. Use this selection when the DTE does not

 

provide RTS to the modem.

 

 

&R2

Simulated Control Carrier. RTS input controls the remote modem's LSD signal. This is used for

 

DTEs that require Line Signal Detect (LSD) to toggle ON and Off to simulate half-duplex operation.

 

 

4-10

January 1999

3821-A2-GB20-40

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Paradyne 3821PLUS manual Mn or &Qn ± Async/Sync Mode and DTE Dialer Type, M0, &Q, &Q0, Rn ± RTS Action