Instruction manual

Guppy PRO Technical ManualV4.1.0
175
How does bandwidth affect the frame rate?
How does bandwidth affect the frame
rate?
In some modes the IEEE 1394b bus limits the attainable frame rate. According to
the 1394b specification on isochronous transfer, the largest data payload size of
8192 bytes per 125 μs cycle is possible with bandwidth of 800 Mbit/s. In addi-
tion, there is a limitation, only a maximum number of 65535 (2
16
-1) packets per
frame are allowed.
The following formula establishes the relationship between the required
Byte_Per_Packet size and certain variables for the image. It is valid only for For-
mat_7.
If the value for BYTE_PER_PACKET is greater than 8192 (the maximum data pay-
load), the sought-after frame rate cannot be attained.
The attainable frame rate can be calculated using this formula:
(Provision: BYTE_PER_PACKET is divisible by 4):
ByteDepth is based on the following values:
Note

Certain cameras may offer higher packet sizes, depending on
their settings in combination with the use of FirePackage.
Consult your local dealer's support team, if you require addi-
tional information on this feature.
Formula 19: Byte_per_Packet calculation (only Format_7)
Formula 20: Maximum frame rate calculation
Mode bit/pixel byte per pixel
Mono8, Raw8 8 1
Mono12, Raw12 12 1.5
Mono16, Raw16 14 2
YUV4:2:2 16 2
RGB8 24 3
Table 103: ByteDepth
BYTE_PER_PACKET frame rate AOI_WIDTH AOI_HEIGHT ByteDepth 125 μs=
frame rate
BYTE_PER_PACKET
AOI_WIDTH AOI_HEIGHT ByteDepth 125 μs
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