Transfer Control

The Transfer Control category contains features that control the transferring of image data to the host.

An acquisition generates frames that are optionally processed and may have extra data appended (chunk data) before being placed in the transfer queue for transmission out of the device. Once the image data has gone through any processing and had the appropriate data appended it is referred to as a block. These blocks are then handed to the transfer module to be sent out of the device on data streams. The transfer module then transmits these blocks externally on stream channels.

This can be manually or automatically controlled. Use the Transfer Control Mode to select the control method. There are three options: Basic, Automatic, and User Controlled.

In both Basic and Automatic mode the camera starts transmitting data as soon as there is enough data to fill a link layer packet. This reduces the latency between when the image was acquired and when it is available to the user. As long as the link layer is able to transfer data blocks faster than they are being generated the camera continuously sends one image after another on the stream channel.

There is a Transfer Queue which starts to fill up if the link slows down.

The Transfer Queue Max Block Count indicates the transfer queue's maximum capacity.

The Transfer Queue Current Block Count indicates the number of blocks currently in the transfer queue.

The Transfer Queue Overflow Count indicates the number of blocks that have been lost before being transmitted.

The Transfer Queue Mode indicates the mechanism for transmitting and overwriting blocks in the transfer queue. It is First In First Out, which means the oldest block in the queue is always sent next on the stream channel.

Once the transfer queue is full the camera overwrites the oldest block in the queue with the new block arriving from the acquisition and processing modules that has not already begun being transmitted. At this point the Queue Overflow is incremented. Once the image that is currently being transmitted finishes, the transmission module transmits the next oldest image in the transfer queue.

In User Controlled mode you can directly control the transfer of blocks. Use the Transfer Operation Mode to select an operation mode. There are two options: Continuous and Multi Block.

Continuous sends images without stopping in the same manner as Basic/Automatic, but you can use Transfer Start and Transfer Stop to control the streaming while acquisition runs independently.

Multi Block transmits a specified number of blocks and then stops. Use the Transfer Block Count to specific the number of blocks. Use the Transfer Start command to initiate a multi block transfer.

Note: Acquisition can be started and stopped without affecting the transfer queue or transfer state however closing the stream channel clears both the queue and any pending transmissions.

Summary Table

Name	Interface	Access	Visibility	Description
Transfer Control Mode	IEnumeration	RW	Expert	Selects the control method for the transfers. Basic and Automatic start transmitting data as soon as there is enough data to fill a link layer packet. User Controlled allows you to directly control the transfer of blocks.
Transfer Operation Mode	IEnumeration	RW	Expert	Selects the operation mode of the transfer. Continuous is similar to Basic/Automatic but you can start/stop the transfer while acquisition runs independently. Multi Block transmits a specified number of blocks and then stops.
Transfer Block Count	IInteger	RW	Expert	Specifies the number of data blocks (images) that the device should stream before stopping. This feature is only active if the Transfer Operation Mode is set to Multi Block.
Transfer Queue Max Block Count	IInteger	RO	Expert	Returns the maximum number of data blocks (images) in the transfer queue
Transfer Queue Current Block Count	IInteger	RO	Expert	Returns number of data blocks (images) currently in the transfer queue.
Transfer Queue Overflow Count	IInteger	RO	Expert	Returns number of images that have been lost before being transmitted because the transmit queue hasn't been cleared fast enough.
Transfer Queue Mode	IEnumeration	RW	Expert	Specifies the operation mode of the transfer queue.
Transfer Start	ICommand	WO	Expert	Starts the streaming of data blocks (images) out of the device. This feature is available when the Transfer Control Mode is set to User Controlled.
Transfer Stop	ICommand	WO	Expert	Stops the streaming of data block (images). The current block transmission is completed. This feature is available when the Transfer Control Mode is set to User Controlled.

Transfer Control Features

Transfer Control Mode

Selects the control method for the transfers. Basic and Automatic start transmitting data as soon as there is enough data to fill a link layer packet. User Controlled allows you to directly control the transfer of blocks.

Property	Value
Name	TransferControlMode
Interface	IEnumeration
Access	RW
Visibility	Expert

Enumeration Values
Basic
Automatic
UserControlled

Transfer Operation Mode

Selects the operation mode of the transfer. Continuous is similar to Basic/Automatic but you can start/stop the transfer while acquisition runs independently. Multi Block transmits a specified number of blocks and then stops.

Property	Value
Name	TransferOperationMode
Interface	IEnumeration
Access	RW
Visibility	Expert

Enumeration Values
Continuous
MultiBlock

Transfer Block Count

Specifies the number of data blocks (images) that the device should stream before stopping. This feature is only active if the Transfer Operation Mode is set to Multi Block.

Property	Value
Name	TransferBlockCount
Interface	IInteger
Access	RW
Unit
Visibility	Expert

Transfer Queue Max Block Count

Returns the maximum number of data blocks (images) in the transfer queue

Property	Value
Name	TransferQueueMaxBlockCount
Interface	IInteger
Access	RO
Unit
Visibility	Expert

Transfer Queue Current Block Count

Returns number of data blocks (images) currently in the transfer queue.

Property	Value
Name	TransferQueueCurrentBlockCount
Interface	IInteger
Access	RO
Unit
Visibility	Expert

Transfer Queue Overflow Count

Returns number of images that have been lost before being transmitted because the transmit queue hasn't been cleared fast enough.

Property	Value
Name	TransferQueueOverflowCount
Interface	IInteger
Access	RO
Unit
Visibility	Expert

Transfer Queue Mode

Specifies the operation mode of the transfer queue.

Property	Value
Name	TransferQueueMode
Interface	IEnumeration
Access	RW
Visibility	Expert

Enumeration Values
FirstInFirstOut

Transfer Start

Starts the streaming of data blocks (images) out of the device. This feature is available when the Transfer Control Mode is set to User Controlled.

Property	Value
Name	TransferStart
Interface	ICommand
Access	WO
Visibility	Expert

Transfer Stop

Stops the streaming of data block (images). The current block transmission is completed. This feature is available when the Transfer Control Mode is set to User Controlled.

Property	Value
Name	TransferStop
Interface	ICommand
Access	WO
Visibility	Expert

Blackfly®S BFS-U3-63S4-BD
Camera Reference