The Basler Filter Driver - Basler ace acA640-90gm User Manual

Basler Network Drivers and Parameters
A.1

The Basler Filter Driver

The Basler filter driver is a basic driver GigE Vision network driver. It is designed to be compatible
with most network adapter cards.
The functionality of the filter driver is relatively simple. For each frame, the driver checks the order
of the incoming packets. If the driver detects that a packet or a group of packets is missing, it will
wait for a specified period of time to see if the missing packet or group of packets arrives. If the
packet or group does not arrive within the specified period, the driver will send a resend request for
the missing packet or group of packets.
The parameters associated with the filter driver are described below.
Enable Resend - Enables or disables the packet resend mechanism.
If packet resend is disabled and the filter driver detects that a packet has been lost during
transmission, the grab result for the returned buffer holding the image will indicate that the grab
failed and the image will be incomplete.
If packet resend is enabled and the driver detects that a packet has been lost during transmission,
the driver will send a resend request to the camera. If the camera still has the packet in its buffer, it
will resend the packet. If there are several lost packets in a row, the resend requests will be
combined.
Packet Timeout - The Packet Timeout parameter defines how long (in milliseconds) the filter driver
will wait for the next expected packet before it initiates a resend request. Make sure the Packet
Timeout parameter is set to a longer time interval than the time interval set for the inter-packet
delay.
Frame Retention - The Frame Retention parameter sets the timeout (in milliseconds) for the frame
retention timer. Whenever the filter driver detects the leader for a frame, the frame retention timer
starts. The timer resets after each packet in the frame is received and will timeout after the last
packet is received. If the timer times out at any time before the last packet is received, the buffer for
the frame will be released and will be indicated as an unsuccessful grab.
You can set the filer driver parameter values from within your application software by using the
Basler pylon API. The following code snippet illustrates using the API to read and write the
parameter values:
// Enable Resend
Camera_t::StreamGrabber_t StreamGrabber ( Camera.GetStreamGrabber(0) );
StreamGrabber.EnableResend.SetValue(false); // disable resends
// Packet Timeout/FrameRetention
Camera_t::StreamGrabber_t StreamGrabber ( Camera.GetStreamGrabber(0) );
StreamGrabber.PacketTimeout.SetValue( 40 );
StreamGrabber.FrameRetention.SetValue( 200 );
You can also use the Basler pylon Viewer application to easily set the parameters.
For more information about the pylon API and the pylon Viewer, see Section 3 on
260
page 27.
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