Datalogic GWY-01-PBS-01, Справочное руководство

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GWY-01-PBS-01
48
5
Byte 0 is the Input Buffer Control Byte. The Slave uses the lowest four bits of this byte for
handshaking: to acknowledge receiving a command from the master (Bit 1), and to signal
that a response is ready for the master (Bit 0).
INPUT BUFFER CONTROL BYTE
7 6 5 4 3 2 1 0
[1] [0] [0] [0] [0] [0] [0] [0]
Bit 0 is toggled by the Slave when it has a new packet (response or response
fragment) ready for the Master.
Bit 1
is toggled by the Slave to acknowledge a packet (command or command
fragment) from the Master.
Bit 2
is set by the Slave after it completes resynchronization, and then cleared once
the Master has acknowledged that resynchronization is complete.
Bit 3
is set by the Slave when the total CBx response being returned to the Master is
larger than the space available in the Input Buffer (or that the packet being returned is
a fragment, and that there are more fragments to follow). This bit is cleared for the
final fragment of a fragmented response – and so the Master can know when all the
fragments of a response have been returned from the Slave.
Bit 7
is set to 1 as soon as the Slave has been successfully initialized at power-up,
and remains at 1, to conform to Datalogic’s proprietary “DAD” Protocol.
Byte 1 : is always 0.
Byte 2 : contains the length of the packet in bytes (CBx response or response fragment) to be
sent back to the Master.
Byte 3 through Byte N-2 are used for the actual CBx response or response fragment to be
sent.
Byte N-1: The final byte of the Input Buffer is the Data Consistency Byte for the Input Buffer.
It is a copy of the Input Buffer Control Byte. The Master should check that these two bytes
are the same, before considering the Input Buffer’s data to be valid.
NOTE
The input and output buffers can exceed 64 bytes. The combined total of the
input and output buffers cannot exceed 152 bytes.
5.5.1 Example 1: Normal Command/Response Sequence
For this example, the Master will send a CBx “Read Tag ID” command to the Slave (the
RFID Controller) to read an 8-byte tag ID from an RFID Tag. First we will see a “Tag Not
Found” error (assuming that the tag is not read) and then we will see a successful read of the
Tag ID.