User's Manual

Brooks Automation
62 260301 Revision A
7 Operation ATR60LF RFID Reader CAN Bus
7.5 Operation of the SECS Protocol Product Manual
7.5.5 SECS-II Implementation
Introduction The SEMI Equipment Communication Standard Part 2 (SECS-II) defines
how messages exchanged between intelligent equipment and a host are
interpreted.
It is the intent of this standard to be fully compatible with SEMI Equipment
Communication Standard E4 (SECS-I).
The messages defined in this specification support the typical activities
required for the BROOKS RFID reader.
SECS-II gives form and meaning to messages exchanged between the
equipment and the host using a message transfer protocol, such as SECS-I.
SECS-II defines the method of conveying information between the
equipment and the host in the form of messages.
These messages are organized into categories of activities, called streams,
which contain specific messages, called functions. In SECS-II, messages
are identified by a stream code (0-127, 7 bits) and a function code (0-255,
8 bits). Each combination of stream and function represents a unique
message identification.
SECS-II defines the structure of messages into entities called items and
lists 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 that 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
below.
A list is an ordered set of elements, whereby an element can be either an
item or a list. The list header has the same form as an item header with
Byte Name Description
0 Format and
number of
the length
bytes
The data format is coded in the upper
6
bits.
The two less significant bits determine
the number of the following length
bytes.
1
1-2
1-3
Length bytes The length corresponds to the number
of the bytes of a data element. In the
"List" format, the length corresponds to
the number of the list elements.
The standard does not require the
minimum possible number of length
bytes for a given data length.
Next
<Length>
Data Data bytes of a data element or
number of the data elements in case of
the "List" format.