Rs-232 control information, Visca command/ ack protocol, Overview of visca – Polycom Ceiling DocCam User Manual

Page 12: Visca communication specifications

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Ceiling DocCam II — Appendix

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Ceiling DocCam II — Appendix

20

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• Error message

When a command or inquiry command could not be executed or failed, an error message is
returned instead of the completion message.

Command execution cancel

To cancel a command which has already been sent, send the IF_Clear command as the next
command. To cancel one of any two commands which have been sent, use the cancel message.

Cancel Packet

Cancel

81 21 FF

An error message will be returned for this command, but this is not a fault. It indicates that the
command has been cancelled.

VISCA Command/ ACK Protocol

Command

Command Message

Reply Message

Comments

General Command

81 01 04 38 02 FF
(Example)

90 41 FF (ACK)+90 51 FF
(Completion)
90 42 FF 90 52 FF

Returns ACK when a command has been
accepted, and Completion when a
command has been executed.

81 01 04 38 FF
(Example)

90 60 02 FF (Syntax Error)

81 01 04 38 02 FF
(Example)

90 60 03 FF
(Command Buffer Full)

There are two commands currently being
executed and the command could
not be accepted.

81 01 04 08 02 FF
(Example)

90 61 41 FF
(Command Not Executable)
90 62 41FF

Could not execute the command in the
current mode.

Inquiry Command

81 09 04 38 FF
(Example)

90 50 02 FF (Completion)

ACK is not returned for the inquiry command.

81 09 05 38 FF
(Example)

90 60 02 FF (Syntax Error)

Accepted an incompatible command.

Address Set

88 03 01 FF

88 30 02 FF

Returned the device address to +1.

IF_Clear(Broadcast)

88 01 00 01 FF

88 01 00 01 FF

Returned the same command.

IF_Clear (for x)

81 01 00 01 FF

z0 50 FF (Completion)

ACK is not returend for this command.

Command Cancel

81 21 FF

z0 61 04 FF
(Command Canceled)

Returned when the command of the socket
specified is cancelled.
Completion for the command cancelled is
not returned.

z0 61 05 FF

Returned when the command of the specified
socket has already been completed or when
the scoket number specified is wrong.

Accepted a command which is not
supported or a command lacking
parameters.

90 61 01 FF

Message length error (>14 bytes)

90 61 02 FF

Syntax Error

90 61 03 FF

Command buffer full

90 61 04 FF

Command Cancelled

90 61 05 FF

No socket (to be cancelled)

90 61 41 FF

Command not executable

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RS-232 control information

Note: For best performance of the VISCA commands, set DIP switches to the ClearOne
configuration when the camera is connected to the control port of a codec.

Overview of VISCA

In VISCA a device that sends commands,such as a computer, is called the controller. The device that
receives commands such as a camera is called the peripheral device. The parameters of RS-232C are
as follows.

Communication speed: 9.6 kbps/19.2 kbps/38.4 kbps

• Data bits: 8

• Start bit: 1

• Stop: 1

• Non parity

Flow control using XON/XOFF and RTS/CTS, etc., is not supported.

VISCA Communication Specifications

Command and inquiry

• Command

Sends operational commands to the camera.

• Inquiry

Used for inquiring about the current state of the camera.

Command Packet

Note

Inquiry

81 QQ RR ... FF

QQ

1)

= Command/Inquiry

RR

2)

= Category code

1)

QQ = 01 (Command), 09 (Inquiry)

2)

RR = (Interface), 04 (camera 1), 06 (Pan.Tilter), 07 (camera 2)

Responses for commands and inquiries

• ACK Message

Returned by the camera when it receives a command. No ACK message is returned for inquiries.

• Completion message

Returned by the camera when execution of commands or inquiries is completed. In the case of
inquiry commands, it will contain reply data for the inquiry after the 3rd byte of the packet. If
the ACK message is omitted, the socket number will contain 0.

Reply Packet

Ack

90 41 FF

Completion (commands)

90 51 FF

Completion (inquiries)

90 51 FF

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