Communicating with the Video Switch
Communicating Using VISCA
Note! This section applies only to users wanting to control the switch directly from an external control system connected to Data port 3 on the switch.
The following describes how to communicate with the TANDBERG Video Switch using the VISCA protocol. For details about the protocol implementation, refer to the System Integrators Guide – Interfacing to the TANDBERG Wave 2 Camera.
VISCA Interface Basics
The TANDBERG Video Switch (TVS) uses a
TVS is configured in exactly the same way as a VISCA camera. TVS will always be located first in the camera chain(s).
The main jobs of the VISCA interface in the TVS are:
•Select which video source to use
•Route VISCA messages to the connected cameras
•Control picture resolutions sent to the codec
Cameras chained to the switch will start with id 2. The codec will automatically recognize this and map the cameras accordingly.
VISCA Serial Ports
The switch has a total of 4 serial ports that communicate using the VISCA protocol.
•Port 0, on the THSI interface, is always connected to the codec.
•Port 1 is the primary VISCA chain for cameras connected to the Switch.
•Port 2 is the secondary VISCA chain for the cameras that normally are connected to codec video inputs
•Port 3 is intended for external control systems, and works in the same way as port 0, but with some limitations on available commands. It is comparable to running the daisy port on a TANDBERG Precision HD Camera in dualvisca mode.
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This article covers the use of port 3 as the control port for the switch. You may use port 0 if you do not intend to use the THSI interface, but only use HDMI out.
Enhanced VISCA
Since the switch has two possible camera chains, all normally formatted commands will be sent to the primary chain. To access the secondary chain, you must first turn Enhanced VISCA on with the SW_eVisca command.
Commands going to the secondary chain must be prefixed with FE 01. Replies from the secondary chain will also be prefixed with FE 01. You will only receive push messages from the secondary chain if Enhanced VISCA is turned on.
Important: Since the switch can receive VISCA from either the codec or an external control system, and since there are two possible camera chains, there are limitations on how commands are issued and answered:
•Only one command can be processed at a time
•Sending a new command when you receive an ACK from a Sony camera is not allowed. ACK messages will be thrown away by the switch
•Reply will always go to the source that issued the command.
•Sony push messages will be sent to both sources.
If this is not expected behaviour, an external control system may, of course, be setw to control all connected cameras directly via VISCA.
VISCA Messages
Commands that are prefixed with SW_ are new for the switch. The CAM_ prefix is used for commands that are copied from TANDBERG Precision HD Camera, or are standard VISCA messages.
VISCA Standard Commands
Command Set |
| Command Packet | Comments |
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CAM_IF_Clear | 8x | 01 00 01 ff | Clear command buffer. Stop any current |
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| operation in progress. |
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CAM_Address_Set | 8x | 30 0p ff | p = address for this device. If x=8 |
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| (broadcast), increase p with 1 before |
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| sending to chain. |
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CAM_Command_Cancel | 8x | 2p ff | p = Socket ID. Not supported in TVS |
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CAM_Power | 8x | 01 04 00 0p ff | p = 2: Power on. p = 3: Power off. |
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VISCA Standard Inquiries
Command | Command Packet | Comments |
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IF_DeviceType_Inq | 8x 09 00 02 ff | y0 50 gg gg hh hh jj jj kk ff |
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| gggg = Vendor ID |
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| hhhh = Model ID |
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| jjjj = ROM Revision |
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| kk = Max sockets |
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| (No support for this in the TANDBERG |
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| Video Switch. Ignore it.) |
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CAM_Power_Inq | 8x 09 04 00 ff | y0 50 0p ff |
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| p = 2: Power on. |
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| p = 3: Power off. |
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VISCA Standard Push Messages
Command | Command Packet | Comments |
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CAM_Network_Change | x0 38 ff | This indicates that cameras have been |
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| added to or removed from the camera |
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| chain. |
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| To avoid issues with (some) Sony |
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| cameras, the control system or |
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| codec should delay 9 seconds before |
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| reconfiguring the chain. |
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