Sony BRC-300P Befehlsliste - Seite 4
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VISCA Communication
Specifications
VISCA packet structure
The basic unit of VISCA communication is called a
packet (Fig. 2). The first byte of the packet is called
the header and comprises the sender's and receiver's
addresses. For example, the header of the packet sent
to the BRC-300/P assigned address 1 from the
controller (address 0) is hexadecimal 81H. The packet
Header
Sender's
address
1
Bit 7
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
(MSB)
Note
Fig. 2 shows the packet structure, while Fig. 3 shows
the actual waveform. Data flow will take place with
the LSB first.
Timing Chart
As VISCA Command processing can only be carried
out one time in a Vertical cycle, it takes the maximum
1V cycle time for an ACK/Completion to be returned.
If the Command ACK/Completion communication
time can be cut shorter than the 1V cycle time, then
every 1V cycle can receive a Command.
From this point, if 2 or more commands in a row are to
be sent, wait for the first command (for normal
commands, an ACK or an error message, for query
commands, an Inquiry Packet) to be carried out before
sending the next one.
Packet (3 to 16 bytes)
Message (1 to 14 bytes)
Byte 1
Byte 2
Receiver's address
0
(LSB)
Fig. 2 Packet structure
Start
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5
bit
(LSB)
Fig. 3 Actual waveform for 1 byte.
sent to the BRC-300/P assigned address 2 is 82H. In
the command list, as the header is 8X, input the
address of the BRC-300/P at X. The header of the
reply packet from the BRC-300/P assigned address 1 is
90H. The packet from the BRC-300/P assigned
address 2 is A0H.
Some of the commands for setting BRC-300/P units
can be sent to all devices at one time (broadcast). In
the case of broadcast, the header should be
hexadecimal 88H.
When the terminator is FFH, it signifies the end of the
packet.
Byte 3
1
1
1
Bit 7
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
(MSB)
1 byte
Bit 6 Bit 7
General Commands
Command
RxD
TxD
Within16.7msec(20msec*PAL)
Query Commands
Command
RxD
TxD
Terminator
FF
1
1
1
1
Stop
bit.
(MSB)
ACK Completion
16.7msec(20msec*PAL)
1
(LSB)
Inquiry Pocket
16 Byte
4