Technical information

Chapter 2: AT+i Commands Reference
May 31, 2008 AT+i Commands Reference Manual 2-63
When several consecutive AT+iEMB commands are used, the host must issue the commands with
an inter-command delay, which does not violate the SMTP server's timeout constraints.
Otherwise, the SMTP server will timeout and abort the session. Average SMTP servers allow for
delays in the range of 30 to 120 seconds. Additional AT+i commands may be interlaced within a
sequence of AT+iEMB commands, except for the following AT+i commands: AT+iEMA,
AT+iRML, AT+iRMH, AT+iRMM, AT+iRFU, AT+iRLNK, AT+iBDRA, and AT+iSNMD.
W24 does not limit the size of the binary attachment. However, ISPs do have limitations. An
Internet connection is initiated immediately after the first AT+iEMB command, while the rest of
the command is received. Once the connection to the SMTP server has been established, W24
acts as a pipeline, receiving binary info from the host, encoding it, and transmitting it to the
Internet on-the-fly. Following the AT+iE* command, the e-mail is terminated and the Internet
connection closed.
The escape sequence command (+++) is allowed within an AT+iEMB command, provided there
is a half-second silence period before the (+++) is sent. Upon receiving the escape sequence, W24
aborts and orderly closes the Internet session. The partial mail message is not sent to the
destination.
Binary Attachment Parameters
Table 2-3 shows the binary attachment parameters.
Defining a Textual Body for Binary Messages
1. Permanent textual body contents:
AT+iBDY:<text lines> … <CR>.<CR>
The maximum fixed body size allowed is 96 characters (including embedded <CR><LF>). The
text body is included in all future binary messages. In addition, the textual contents are committed
to non-volatile memory on board the W24.
2. Single session textual body contents:
AT+iBDY~<text lines> … <CR>.<CR>
Table 2-3: Binary Attachment Parameters
Parameter Default Description
MT 4 (application) Media Type:
0 - Text; 1 - Image ; 2 - Audio ; 3 - Video ;
4 - Application
MST octet-stream Media Subtype String. For a list, see “MIME Content
Types and Subtypes” on page A-1.
FN None Attachment File Name (inc. extension). If a file name
is not defined, W24 generates a unique filename
without an extension.
BDY None ASCII text to be included in the e-mail's body in
addition to the attachment. (Multiple lines allowed).