User manual

Section 4

AT COMMAND SET

4-19

AT&L LEASED Line Select

Parameters : 0 or 1

Default : 0 (Dial Network)

The CCITT V.22bis recommendation is primarily concerned with dial network operation.

Leased line operation with different manufacturers products may not be entirely

successful. The DPX-213 supports leased line operation at 1200 and 2400 bps in both

AT&L0 and AT&L1 modes. Data transfer at 300 bps is only supported in AT&L1 mode and

data transfer at 1200/75 V.23 is not supported in either leased line mode.

AT&L0 - Dial Network Mode.

AT&L1 - Enable speeds 300, 1200 and 2400 bps only. MNP/V42 and the Constant Speed

Interface are disabled in this Mode. Synchronous or Asynchronous Mode is

selected via the AT&Mn commands. The AT&D0 (ignore DTR) effectively

overrides the DTR Pin on the interface. Setting AT&D0 with AT&L1 forces the

DPX-213 on-line immediately regardless of the DTR status. This is the

recommended mode for interworking with the DPX-224 or TEL-424 modems.

Configure the modem for leased line operation as follows:

1. Set AT&D1 mode.

2. Issue the AT&L1 command to select Leased Line Mode.

3. Set register S0=0 at one end to force Originate Mode.

4. Set register S0=1 at the other end to force Answer Mode.

5. Enter AT&M1 mode.

6. Raise DTR at both ends to establish the link.

Once connected the escape sequence 'pause'

+++

'pause' is entered, control may be

regained and allow entering the ATH command if needed. Alternatively, the DTR may be

dropped to return to Command Mode. In synchronous (AT&M2 or AT&M1) Mode,

dropping DTR will terminate the call. In asynchronous (AT&M3) Mode, dropping DTR

will follow the AT&Dn command.

All keystrokes are ignored during leased line call establishment phase.

NOTE: The line interface cable must be modified as shown in Appendix D for correct

operation in leased line modes.