Specifications

MC55 AT Command Set
10. Internet Service Commands
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MC55_ATC_V03.03 Page 218 of 459 9/9/05
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10. Internet Service Commands
MC55 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
Step-by-step overview of how to configure and use TCP/IP communications with MC55:
• First of all, create a 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. 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 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>. A URC indicates whether data are avail-
able. This is either the "^SISR" URC if the service profile is configured for receiving data, or the "^SISW" URC,
if the service profile is intended for sending data. If an error occurs the "^SIS" URC is delivered instead.
• The next command determines the action to be performed, either reading data with AT^SISR or writing data
with AT^SISW. The first parameter is the <srvProfileId>, the second parameter is the number of bytes
which the host either likes 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 MC55 is 1500 bytes in both directions (read or write).
• Finally, to end a session, enter the AT^SISC write command and the <srvProfileId>.
Maximum number of profiles defined / used:
• Up to 6 connection profiles can be created (with AT^SICS).
• Up to 10 service profiles can be created (with AT^SISS), but the number of parallel profiles of the same ser-
vice type is limited as listed below. If the maximum number of a service profile type is already defined, any
attempt to set up another profile for the same type will be denied with "+CME ERROR: unknown".
- Maximum 3 HTTP profiles
- Maximum 6 socket profiles: The socket service can accept an incoming connection only when at least one
service profile is still free (not yet created with AT^SISS), otherwise the incoming connection will be
rejected from the listener.
- 1 FTP profile
-1 POP3 profile
- 1 SMTP profile
• The TCP/IP stack of MC55 supports one service profile at a time. Trying to run more than one service profile