PROFIBUS INTERFACE
47
5
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 always 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 Command or Command Fragment) to
be sent to the RFID Controller. This can be the length of an entire CBx command, or the
length of a fragment of a command, if the CBx command is larger than the space allowed to
send it in a single fragment.
Byte 3
through Byte N-2
are used for the actual CBx Command or Command Fragment to
be sent.
Byte N-1:
the final byte of the Output Buffer is the
Data Consistency Byte.
It is a copy of
the
Ouptut Buffer Control Byte.
When changes to the Control Byte are made, the same
changes must also be made in the Data Consistency Byte, before the changes “take effect”.
This is to guarantee the validity of the data between the two bytes.
The
INPUT Buffer
is controlled by the Slave (Cobalt RFID Controller) and is mapped the
same way, except for the packet bytes containing a response (or response fragment) from
the controller.
Input Buffer
Byte #
00:
INPUT BUFFER CONTROL BYTE (IBCB)
01: (Always
0)
02:
Packet Length in Bytes
03:
04:
05:
06:
07:
08:
09:
10:
-
-
N-2:
Packet Bytes (Response)
“ “
“ “
“ “
“ “
“ “
“ “
“ “
“ “
“ “
“ “
N-1:
Data Consistency Byte (IBDCB)
Summary of Contents for GWY-01-PBS-01
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