目前，发送短消息常用Text和PDU(Protocol Data Unit)模式。使用Text模式收发短信代码简单，实现起来十分容易，但最大的缺点是不能收发中文短信；而PDU模式不仅支持中文短信，也能发送英文短信。PDU模式收发短信可以使用3种<em>编码</em>：7-bit、8-bit和UCS2<em>编码</em>。7-bit<em>编码</em>用于发送普通的ASCII字符，8-bit<em>编码</em>通常用于发送...
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During my work with the electrical utility industry, several educational issues in regards
to MMS have often been discussed. The issues of understanding the ISO/IEC-9506
standard have always been a core problem for the non-initiated.
For the MMS non-initiated, the MMS standard is a problem since it infers the use of other
standards (e.g., Presentation, ASN.1, and ACSE). Besides not being a self-contained
standard, the division of protocol specification and encoding represents a different
philosophy from many of the previous SCADA protocols. However, given all the
required documentation, it still takes considerable time to understand ASN.1 and MMS.
This document is intended to help boot-strap individuals in the educational process. In
order to achieve an initial understanding of the encoding of MMS, I have intentionally
restricted the included examples of commonly used semantics and protocols.