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VISCA Communication
Specifications
VISCA packet structure
The basic unit of VISCA communication is called a
packet. 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 FCB
camera assigned address 1 from the controller (address
0) is hexadecimal 81H. The packet sent to the camera
Header
Sender's
address
1
Bit 7
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
(MSB)
Command and inquiry
● Command
Sends operational commands to the FCB camera.
● Inquiry
Used for inquiring about the current state of the
FCB camera.
Command Packet
Inquiry
8X QQ RR ... FF
1)
QQ = 01 (Command), 09 (Inquiry)
2)
RR = 00 (Interface), 04 (camera 1), 06 (Pan/Tilter), 07 (camera 2)
X = 1 to 7: FCB camera address
Packet (3 to 16 bytes)
Message (1 to 14 bytes)
Byte 1
Byte 2
Receiver's address
0
(LSB)
Note
QQ
1)
= Command/Inquiry,
2)
RR
= category code
assigned address 2 is 82H. In the command list, as the
header is 8X, input the address of the camera at X. The
header of the reply packet from the camera assigned
address 1 is 90H. The packet from the camera assigned
address 2 is A0H.
Some of the commands for setting cameras 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)
Command List
Terminator
FF
1
1
1
1
1
(LSB)
29
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