User's Manual

RS232-Transponder Reader
(SECS1-Protocol), Release 0.3 Draft Page 40 of 91
2000-09-29
ID: ID000093
8.2 SECS-2 Implementation
8.2.1 Introduction
The SEMI Equipment Communication Standard Part 2 (SECS-2) defines
the details of the interpretation of messages exchanged between intelligent
equipment and a host.
It is the intent of this standard to be fully compatible with SEMI Equipment
Communication Standard E4 (SECS-1).
The messages defined in this specification support the typical activities
required for the HERMOS SECS-1 transponder reader.
SECS-2 gives form and meaning to messages exchanged between
equipment and host using a message transfer protocol, such as SECS-1.
SECS-2 defines the method of conveying information between equipment
and host in the form of messages.
These messages are organized into categories of activities, called streams,
which contain specific messages, called functions. In SECS-2, messages
are identified by a stream code (0-127, 7bits) and a function code (0-255,
8 bits). Each combination of stream and function represents a distinct
message identification.
SECS-2 defines the structure of messages into entities called items and list
of items. These data structures define the logical divisions of the message,
as distinct from the physical division of the message transfer protocol.
An item is an information packet which has a length and format defined by
the first 2,3, or 4 bytes of the item. These bytes are called the item header.
The item header consists of the format byte and the length byte as shown.