Balluff BIS M-370-000-A02, Manual, Page: 182 / 198

PROFINET INTERFACE
175
10
10.4.5 Application Data Buffer
The Application data buffer holds the CBx commands described in the CBx Command
Protocol Manual.
10.5 EXAMPLES OF PROFNET COMMAND/RESPONSE MECHANISM
As seen in par. 10.3, there are two buffers
– an OUTPUT Buffer that is controlled by the
MASTER, and an INPUT Buffer that is controlled by the slave (the Controller).
The
OUTPUT Buffer is mapped the following way:
Output Buffer
Byte #
00: OUTPUT BUFFER CONTROL BYTE (OBCB)
01: (Always 0)
02: Packet Length in Bytes
03:
04:
05:
06:
07:
08:
09:
10:
-
-
N-2: Packet Bytes (Command)
“ “
“ “
“ “
“ “
“ “
“ “
“ “
“ “
“ “
“ “
N-1: Data Consistency Byte (OBDCB)
Byte 0 is the Output Buffer Control Byte . The Master uses the lowest two bits of this byte
for handshaking: to signal that a command is ready for the slave ( Bit 1 ), and to acknowledge
receiving a response from the slave ( Bit 0 ).
OUTPUT 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 Master to acknowledge a packet (response) from the RFID Controller.
Bit 1 is toggled by the Master when it has a packet (command) ready for the RFID Controller.
Bit 2
is set when the Master wishes to initiate a “Resynchronization” with the Slave, and then
cleared when it sees the corresponding handshake from the Slave, (indicating that the
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.