User's Manual

OPERATION 5

HF5x Transponder Reader (SECS1-Protocol), Release 1.4

5.4 SECS-2 Implementation

5.4.1 Introduction

The SEMI Equipment Communication Standard Part 2 (SECS-2)

defines details 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-1).

The messages defined in this specification support the typical activities

required for the BROOKS transponder reader.

SECS-2 gives form and meaning to messages exchanged between the

equipment and the host using a message transfer protocol, such as

SECS-1. SECS-2 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-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 unique message identification.

SECS-2 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.

Byte Name Description

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.

1-2

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

Data

Data bytes of a data element or number of the

data elements in case of the “List” format.