Sierra Wireless DART 200 CDPD Modem manual Repeat, Answer Online, Dial connection setup

DART 200 CDPD Modem User’s Guide F DART AT Command Set

Table F-1. Commands beginning with letters

A/ Repeat

Repeats the last AT command.

NOTE:

An AT is not required preceding this command.

AAnswer Online

Causes the DART to stop accepting commands and to wait for an incoming connection request on the active listening port (see also, *L command) for the amount of time specified in S Reg 7 (default - 20 seconds). If a pending connection request (Ring) is already present, the DART accepts the connection and enters the online state.

Usually issued in response to the RING message generated by a connection establishment request (Dial) from a TCP client, or the initial incoming data packet from a UDP client. For TCP the reception of the initial SYN packet from the client initiates the RING.

Any following commands on the same command line are ignored. If input is detected prior to entering online mode, the command is aborted.

After the incoming call is answered, either by an ATA or by setting S-Register 0 = 1, the source address of the caller (IP Address and port number) is available in S-Register 53 and can be viewed by an ATS53?. It cannot be determined by performing an AT&V and viewing S-Register 53.

NOTE:

The preferred method of responding to an incoming connection request is to have the modem in permanent auto-answer mode (by setting S-Register 0 = 1).

Format:
ATA	Answer online
Result codes:
CONNECT	Connection is established
NO CARRIER	Connection not established due to time-out
ERROR	Connection already established

DDial (connection setup)

Issued by a client device to establish a communication session with a server device. What actually occurs depends on whether a TCP (also telnet) or a UDP session is being initiated.

For TCP (or telnet) the DART accepts a connection setup request containing a destination address and optional port, validates it, transmits it to the network, and waits for a response from the server device.

For a DART server an incoming connection request causes a RING message to be generated. If auto answer is not specified by setting S-Register 0 = 1, the Ring message is repeated every 10 seconds for a total of 60 seconds. If the call is not answered by the server (either automatically or with an ATA) within the 60-second time period, a NO ANSWER message is returned to the TCP client.

For UDP the DART accepts the connection setup request, validates it, and stores the destination and optional port number for later use and enters online mode. However, at this point the server is unaware of the UDP Dial. No communication with the UDP server occurs until the client sends a data block to the modem. The data will be combined with the previously stored destination address and transmitted to the network for routing to the UDP server.

Sierra Wireless, Inc. F-2