ThingMagic Autonomous Configuration Tool - Manual (Page 22)

Processing Data from the Reader
Autonomous Configuration Tool v1.0 User Guide 22
Processing Data from the Reader
Sample Response Processing Code
Strictly speaking, once in autonomous mode the reader no longer requires a host API.
However, for practical purposes the data coming from the reader still needs to be parsed.
In the current release data is only available in the
Reader Data Packet Format which can
be difficult to parse, depending on the specific configuration chosen. To facility handling
the data, sample parsing code has been provided in C, C# and Java.
See the README.TXT in autoread-1.25.x.x package for steps to run each parsing
sample.
Reader Data Packet Format
The following table defines the format of the generic Response Packet sent from the
reader to the host.
The fields are summarized in the following table.:
Table 4: Reader Message Packet Format
Field Length Description
Header (Hdr) 1 byte Defines the start of the packet. Equal to 0xFF
Data Length (Len) 1 byte Defines the length, M, of the data field contained in the
packet. Length can be 0 – 248 bytes
OpCode 1 byte Indicates the type of message to follow
Status Word 2 bytes
• Specifies the status of the last command, Successful =
0x0000, else it contains a fault code.
• For Autonomous Operation 0x0400 indicates a read-cycle
start message...also acts as a heartbeat when the reader
is reading but no tags are in the field.
Data M bytes
(0 to 248)
Defines the binary data returned by the reader in response
to a command. This could, for example, represent data read
from a transponder. Data length, M, can be a minimum of 0
and a maximum of 248 bytes.
CRC-16
Checksum 2 bytes CRC-16 checksum (high order byte first). CRC polynomial is
CCITT CRC-16, with a preload of 0xFFFF. This does not
fully specify the operation of the CRC, see
CCITT CRC-16
Calculation .