Instruction manual
Guppy Technical ManualV7.4.0
177
Video formats, modes and bandwidth
As a reference it uses a grid of up to 65534 sample points (in 2
n
steps) equally
spread over the AOI.
Frame rates
An IEEE 1394 camera requires bandwidth to transport images.
The IEEE 1394a bus has very large bandwidth of at least 32 MByte/s for transfer-
ring (isochronously) image data. Per cycle up to 4096 bytes (or around 1000
quadlets = 4 bytes@ 400 Mbit/s) can thus be transmitted.
Depending on the video format settings and the configured frame rate, the cam-
era requires a certain percentage of maximum available bandwidth. Clearly, the
bigger the image and the higher the frame rate, the more data requires transmis-
sion.
The following tables indicate the volume of data in various formats and modes to
be sent within one cycle (125 μs) at 400 Mbit/s of bandwidth.
The tables are divided into three formats:
They enable you to calculate the required bandwidth and to ascertain the num-
ber of cameras that can be operated independently on a bus and in which mode.
Note
Autofunction AOI is independent from Format_7 AOI settings.
If you switch off autofunction AOI, work area position and work
area size follow the current active image size.
To switch off autofunctions, carry out following actions in the
order shown:
1. Uncheck Show AOI check box (SmartView Ctrl2 tab).
2. Uncheck Enable check box (SmartView Ctrl2 tab).
Switch off Auto modi (e.g. Shutter and/or Gain) (SmartView
Ctrl2 tab).
Note
All bandwidth data is calculated with:
1 MByte = 1024 kByte
Format Resolution Max. video format
Format_0 up to VGA 640 x 480
Format_1 up to XGA 1024 x 768
Format_2 up to UXGA 1600 x 1200
Table 75: Overview fixed formats