Industrial Cameras FAQ/TeliGevViewer detects BG serie...
TeliGevViewer detects BG series camera, but captures no images.（No.328）
The image data transmission related parameters of the BG series cameras are optimized so that a camera can complete sending an image as fast as possible. However, a PC may not be able to correctly handle incoming image data due to the excessively dense packet arrivals. Such a case tends to corrupt image acquisition engines then users would notice the phenomenon having seen a displayed frame rate which is obviously slower than their expectation.
If you faced such a situation, keep increasing GevSCPD (GigE Vision Stream Channel Packet Delay) until the situation get better. However, GevSCPD is a feature which controls the gap between each image data packet so if you don't stop increasing the value, an image will consume excessive time to complete transmitting a single image data. It will eventually slows the frame rate.
Some camera models do not allow you to change GevSCPD during image acquisition. In such a case, please stop image acquisition in advance then write a value to GevSCPD.
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The image data sent from a camera is divided into multiple packets. Time interval between each packet is determined by the value of GevSCPD node.
GevSCPD node has parameter to determine the gap between the nearest image data packets. The unit of GevSCPD node is "tick" and the tick is defined by the time stamp frequency of the camera. The frequency can be read from the GevTimestampTickFrequency node.
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The following example calculates GevSCPD that can send image data at 125 fps in VGA, Mono 8 format. Assume the time stamp counter frequency is 62.5 MHz and the packet size is 1500 bytes. In the following example we ignore both the leader and the trailer that are appended to a single image data payload packet.
Payload size of the image data is 640 x 480 x 1 = 307,200 Bytes.
Then a single image data will be divided into 307,200 / 1500 (Packet size) = 205 packets.
Assuming that Ethernet transmits data at 900 Mbps, it will take 307,200 * 8 / 900 / 1024 / 1024 = 2.604 msec to complete transmitting an image data.
At 125 fps, one frame is transmitted in 8 msec, so no image is sent during 8.0 - 2.604 = 5.396 msec.
Having above calculation, if you set GevSCPD a value smaller than 0.005396 / (205 - 1) * 62, 500,000 = 1,653 ticks, you can keep acquiring images at 125 fps but also extending the gap between nearest image packets to moderate the density of data arrivals at the host computer.
The calculation model introduced here had been simplified to show the outline, so please note that you would have to consider other minor factors when you try to calculate an actual SCPD value and it typically get more or less larger than the one you calculated following the above example.
If you faced such a situation, keep increasing GevSCPD (GigE Vision Stream Channel Packet Delay) until the situation get better. However, GevSCPD is a feature which controls the gap between each image data packet so if you don't stop increasing the value, an image will consume excessive time to complete transmitting a single image data. It will eventually slows the frame rate.
Some camera models do not allow you to change GevSCPD during image acquisition. In such a case, please stop image acquisition in advance then write a value to GevSCPD.
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The image data sent from a camera is divided into multiple packets. Time interval between each packet is determined by the value of GevSCPD node.
GevSCPD node has parameter to determine the gap between the nearest image data packets. The unit of GevSCPD node is "tick" and the tick is defined by the time stamp frequency of the camera. The frequency can be read from the GevTimestampTickFrequency node.
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The following example calculates GevSCPD that can send image data at 125 fps in VGA, Mono 8 format. Assume the time stamp counter frequency is 62.5 MHz and the packet size is 1500 bytes. In the following example we ignore both the leader and the trailer that are appended to a single image data payload packet.
Payload size of the image data is 640 x 480 x 1 = 307,200 Bytes.
Then a single image data will be divided into 307,200 / 1500 (Packet size) = 205 packets.
Assuming that Ethernet transmits data at 900 Mbps, it will take 307,200 * 8 / 900 / 1024 / 1024 = 2.604 msec to complete transmitting an image data.
At 125 fps, one frame is transmitted in 8 msec, so no image is sent during 8.0 - 2.604 = 5.396 msec.
Having above calculation, if you set GevSCPD a value smaller than 0.005396 / (205 - 1) * 62, 500,000 = 1,653 ticks, you can keep acquiring images at 125 fps but also extending the gap between nearest image packets to moderate the density of data arrivals at the host computer.
The calculation model introduced here had been simplified to show the outline, so please note that you would have to consider other minor factors when you try to calculate an actual SCPD value and it typically get more or less larger than the one you calculated following the above example.