Sierra Wireless DART 200 CDPD Modem Application Programming, AT Command Set Support, Chapter

Chapter
8	Application Programming
	The Data Access Radio Transceiver (DART) 200 offers built-in
	Transmission Control Protocol (TCP), User Datagram Protocol (UDP),
	Serial Line Internet Protocol (SLIP), and telnet support, but most
	end-user application programming that interacts with the modem uses
	TCP, UDP, or SLIP.
	Telnet is used primarily as a path to applications on remote hosts with
	the local device being an ASCII terminal or, more likely, a PC emulating
	an ASCII terminal. Outside of setting up the modem initially to meet
	telnet’s needs, there is no programming to do. Error handling is provided
	by the ASCII terminal emulator and is usually minimal.
	This chapter is directed at TCP and UDP applications, and DART 200
	solutions, particularly for DART 200 error handling. SLIP mode
	applications function similarly, but the specifics are a function of the
	capabilities of the software stack being used. If you plan on using SLIP,
	refer to the application programming guide for your specific package.

AT Command Set Support

The terminal device, (Mobile Application Subsystem), does not have to support the Attention (AT) command set directly to operate with the DART 200. Even in cases where the device does support the basic AT command set, there are some extensions to the command set that are not supported. Usually, a programmable device can create a constant string that represents the desired AT command. Sending such a character string to the DART 200 works the same as sending the AT command.

If the remote device is of limited intelligence it does not need to support the AT command set at all. The modem can be pre-initialized to work with the remote device, including being in auto answer mode. In auto answer mode, when the modem receives a connection request (TCP mode), or a datagram (UDP mode), it goes online and passes data to the attached device, just like a wire-line modem. In this situation, the fact that CDPD is the communications medium is transparent to the remote device.

PN1197-00 Revision 1.0