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19
Command List
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 EVI-D100/P assigned address 1 from the
controller (address 0) is hexadecimal 81H. The packet
Fig.2 Packet structure
Bit 7
(MSB)
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
(LSB)
10
FF
Bit 7
(MSB)
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
(LSB)
11111111
Packet (3 to 16 bytes)
Message (1 to 14 bytes)Header
Terminator
Byte 1 Byte 2 Byte 3
Sender’s
address
Receiver’s address
sent to the EVI-D100/P assigned address 2 is 82H. In
the command list, as the header is 8X, input the
address of the EVI-D100/P at X. The header of the
reply packet from the EVI-D100/P assigned address 1
is 90H. The packet from the EVI-D100/P assigned
address 2 is A0H.
Some of the commands for setting EVI-D100/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.
Command and inquiry
● Command
Sends operational commands to the EVI-D100/P.
● Inquiry
Used for inquiring about the current state of the
EVI-D100/P.
Command Packet Note
Inquiry 8X QQ RR ... FF QQ
1)
= Command/Inquiry,
RR
2)
= category code
1)
QQ = 01 (Command), 09 (Inquiry)
2)
RR = 00 (Interface), 04 (camera 1), 06 (Pan/Tilter)
X = 1 to 7: EVI-D100/P address