Specifications

Chapter 10 – Internet Service Commands
Multi-Tech Systems, Inc. AT Commands for EDGE (E1) Modems (S000474A) 145
Chapter 10 – Internet Service
Commands
Each Multi-Tech Wireless EDGE device has an embedded TCP/IP stack that is driven by AT commands and enables
the host application to easily access the Internet. The advantage of this solution is that it eliminates the need for the
application manufacturer to implement its own TCP/IP and PPP stacks, thus minimizing cost and time to integrate
Internet connectivity into a new or existing host application. This chapter is a reference guide to all the AT commands
and responses defined for use with the TCP/IP stack.
Access is provided to the following Internet Services:
1. Socket Client and Server for TCP, Client for UDP
2. FTP Client
3. HTTP Client
4. SMTP Client
5. POP3 Client
Two design strategies for using Internet Service AT commands - URC mode or polling mode:
Two modes of controlling an Internet session opened with AT^SISO are available. To select the mode that best suits
the preferences of your application design use the AT^SCFG command, parameter "Tcp/WithURCs" (refer to
<tcpWithUrc>).
• URC mode (delivery default):
The progress of an Internet session is URC driven. The URCs notify the host whether data can be sent or
received, whether data transfer has completed, whether the service can be closed or whether an error has
occurred. This mechanism eliminates the need to poll the service until the necessary progress information is
received.
To enable the URC mode select: AT^SCFG="Tcp/WithURCs",on.
• Polling mode:
In polling mode, the presentation of URCs related to the Internet Services is disabled. The host is
responsible to retrieve all the status information needed for controlling the Internet session. This is done by
polling, where the host application keeps sending the commands AT^SISR, AT^SISW, AT^SISI.
To enable the polling mode select: AT^SCFG="Tcp/WithURCs",off.
The disabled URCs are the following: "^SISR" URC, "^SISW" URC and "^SIS" URC for parameter <urc-
Cause>=0 (Internet service events), but not for <urcCause>=1 or 2 (needed for Socket listener and always
enabled).
Step-by-step instructions on how to configure and use TCP/IP communications:
• Select URC mode or polling mode as described above.
• First of all, create a CSD or GPRS connection profile with AT^SICS. The connection profile is a set of basic
parameters that determine the type of connection to use for an Internet service. Up to 6 connection profiles
can be defined, each identified by the <conProfileId>.
• Secondly, use AT^SISS to create a service profile based on one of the connection profiles. Up to 10 service
profiles can be defined, each identified by the <srvProfileId>. The service profile specifies the type of
Internet service to use, i.e. Socket, FTP, HTTP, or one of the email services SMTP or POP3. To assign a
connection profile to a service profile, the <conProfileId> of AT^SICS must be entered as “conId” value of
the AT^SISS parameter <srvParmTag>.
This offers great flexibility to combine connection profiles and service profiles. For example, you may have
one connection profile (CSD or GPRS) specified with AT^SICS which can be associated with an SMTP
service profile for sending emails and a POP3 service profile for retrieving emails.
• Once the connection profile and the service profile are created, an Internet session can be opened by
entering the AT^SISO write command and the desired <srvProfileId>.
In URC mode, the "^SISR" or "^SISW" URC indicates whether the service is ready to receive or send data.
This means that the AT^SISR or AT^SISW command shall be entered after the URC was received. If an
error occurs the "^SIS" URC is delivered instead.
In polling mode, you can enter the AT^SISR or AT^SISW command straight after AT^SISO though you may
need to do so several times until the service confirms that data can be sent or received.
• The first parameter of the AT^SISR or AT^SISW commands is always the <srvProfileId>, the second
parameter is the number of bytes which the host either wants to send to or is able to receive from the
module. The way the module handles the data transfer follows the rules of the ordinary socket interface and
is aware that a host may be limited by its input buffer size. The maximum data size supported by MC75 is
1500 bytes in both directions (read or write). To send or receive more than 1500 bytes, the read or write
action shall be repeated until the data transfer has completed. Each read or write action requires that the
command response (of AT^SISR or AT^SISW) confirms that the service is ready to send or receive data.
To end an upload data stream set the <eodFlag> in the last AT^SISW command.