Responses

VISCA cameras respond according to the request type. Commands may return an acknowledgement, a completion message, or both; inquiries return an inquiry reply. Either request type can return an error. Every response packet ends with the FF terminator.

Packet Notation

Symbol	Meaning
Y	Reply-address nibble. For VISCA over IP, Y is 9. For serial VISCA, Y is the camera address plus 8 (9 through F for camera addresses 1 through 7).
Z	Command socket number. A camera reports this number in the acknowledgement and the corresponding completion or error.
...	Reply data whose length and meaning depend on the command or inquiry.
FF	Packet terminator.

4Z, 5Z, and 6Z each represent one byte. The first hexadecimal digit identifies the message type, and the second digit is the socket number. For example, socket 1 produces 41, 51, or 61.

Command Responses

Commands may use a command socket and return an acknowledgement, a completion message, or both. When both are sent, the acknowledgement reports that the camera accepted the command, and the completion message reports that execution finished.

Response	Packet	Meaning
Acknowledgement (ACK)	Y0 4Z FF	The camera accepted the command on socket Z.
Completion	Y0 5Z FF	The command on socket Z finished executing.

For VISCA over IP, a command accepted on socket 1 returns 90 41 FF; when that command finishes, the camera returns 90 51 FF.

Match completion and socket-specific error packets to the acknowledgement by their shared socket number. When more than one command is active, completion order can differ from submission order.

Inquiry Replies

Inquiries do not allocate a VISCA command socket and do not return an acknowledgement. A successful inquiry returns a completion reply whose socket-number field is 0, with the requested data following the 50 byte.

Response	Packet	Meaning
Inquiry reply	Y0 50 ... FF	The inquiry completed; ... contains the requested value.

For example, 90 50 02 FF is the VISCA-over-IP reply indicating that camera power is on. See Inquiries for inquiry packets and reply values.

Error Responses

A camera returns an error when it rejects a command or inquiry, or when an accepted command cannot finish. An error may therefore arrive before any acknowledgement or instead of the completion message.

Error	Packet	Meaning
Syntax error	Y0 60 02 FF	The packet format or a command parameter is invalid.
Command buffer full	Y0 60 03 FF	Both command sockets are in use, so the camera cannot accept another command.
Command canceled	Y0 6Z 04 FF	The command assigned to socket Z was canceled. No completion message follows for that command.
No socket	Y0 6Z 05 FF	No command is executing on socket Z, or the specified socket number is invalid.
Command not executable	Y0 6Z 41 FF	The command is valid but cannot run in the camera's current state.

Syntax and command-buffer-full errors use a socket-number field of 0. Errors associated with an assigned command socket identify that socket in Z. A command-not-executable error can also use Z = 0 when the command is rejected before a socket is assigned.