AC75 AT Command Set
10. Internet Service Commands s
AC75_ATC_V01.002 Page 253 of 569 10/30/06
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10. Internet Service Commands
AC75 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 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:
The AC75 offers two modes of controlling an Internet session opened with AT^SISO. 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 overview of how to configure and use TCP/IP communications with AC75:
• 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 which determines the type of connection to use for an Internet service. The connection type is
also referred to as bearer. Up to 6 connection profiles can be defined, each identified by the <conPro-
fileId>.
• 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 ser-
vice 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