TANDBERG 1080p manual Interfacing to the camera using the Visca protocol, Visca messages

PrecisionHD 1080p Camera

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Interfacing to the camera using the VISCA protocol

The TANDBERG PrecisionHD 1080p camera uses an RS-232 control interface that resembles the Sony VISCA™ protocol.

RS232 Parameters

At startup, the communication parameters for the RS232 interface must be set to:

•9600 bits per second

•8 databits

•No parity

•1 stopbit

•No hardware flow control

•No software flow control

All parameters except speed are fixed and not user configurable. The speed may be changed by issuing the Speed command defined on the following pages. All control bytes are pure binary information, i.e. the control bytes are not ASCII- encoded.

The RS232 Message format

...

Command and response exchange

When the camera receives a command, it responds with either:

•	Completion message: 90-5Y-FF
	Returned by camera when execution of
	commands and inquiries are completed.
•	Error packets: 90-6Y-..-FF
	Returned by camera instead of a completion
	message when command or inquiry failed to be
	executed.
	General error messages, unless otherwise
	specified:
	• 90-6Y-01-FF Message length error
		(>14 bytes)
	•	90-6Y-02-FF Syntax error
	• 90-6Y-03-FF Command buffer full
	•	90-6Y-04-FF Command cancelled
	• 90-6Y-05-FF No socket (to be cancelled)
	• 90-6Y-41-FF Command not executable
• Y = socket number
	A camera may contain two buffers so that two
	commands, including the command being

RS232 Commands and inquiries

A list of all the available commands and inquiries together with the result and comments are found in the table on the following pages.

VISCA messages

A particular command is recognized by the message information after the address byte.

Message Format

Commands are initiated from the host (i.e. the codec or any other external controller) to the camera.

After a camera has been issued a command, the camera will generate a response. Commands and responses (messages) have the following format:

•Address byte (1)

•Information bytes (1..14)

•Terminating byte (1)

See the above illustration for details.

The minimum length of any command or response is 3 bytes:

1.Address byte (1): Let us assume there is one host, i.e. the codec (the host is the unit controlling the camera). The host has address 0. The four least significant bits of the address byte contain the address of the receiver. In the case of a broadcast message, the receiver address should be set to 8. When we are operating a single camera, the address is 1. Hence, address bytes in messages from the host are 0x81, and messages from the camera to the host are 0x90 (the protocol allows for up to 7 cameras).

2.Message bytes (1..14): Any number of bytes containing the actual message information. Bytes may have any value in the range 0...254. The value 255 (i.e. hexadecimal FF) is reserved for the terminating byte.

3.Terminating byte (1): All messages must be terminated with a byte containing all 1’s, i.e. decimal 255 (or hexadecimal FF).

executed, can be received.

Note: The PrecisionHD 1080p camera supports a single socket only. Consequently, the Y always assumes the value Y = 0.

There are exceptions to these rules:

•An Initialize message will respond as indicated in the Table of Commands (this message is in fact a broadcast message, and any unit other than the host receiving the broadcast message must pass it on).

•Do not route commands or replies that are longer than 16 bytes through Sony cameras. The easiest way to avoid this is to put the TANDBERG cameras first in the chain. Commands and replies that are longer than 16 bytes are clearly marked below.

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