Allied Vision Technologies MF-145B2 Instruction Manual download pdf (Page 151)

Marlin Technical ManualV.2.7.0

151

Controlling image capture

FVal is active  the sensor is reading out, the camera is busy

In this case the camera must not change horizontal timing so that the trigger

event is synchronized with the current horizontal clock. This introduces a max.

uncertainty which is equivalent to the line time. The line time depends on the

sensor used and therefore can vary from model to model.

FVal is inactive  the sensor is ready, the camera is idle

In this case the camera can resynchronize the horizontal clock to the new trigger

event, leaving only a very short uncertainty time of the master clock period.

Frame memory and deferred image transport

An image is normally captured and transported in consecutive steps. The image

is taken, read out from the sensor, digitized and sent over the 1394 bus.

Deferred image transport

As all Marlin cameras are equipped with built in image memory, this order of

events can be paused or delayed by using the deferred image transport feature.

Marlin cameras are equipped with 8 MB of RAM. The table below shows how many

frames can be stored by each model. The memory operates according to the FIFO

(first in, first out) principle. This makes addressing for individual images unnec-

essary.

Model Camera idle Camera busy

Marlin F-033 33.33 ns 27.03 μs

Marlin F-046 33.33 ns 32.17 μs

Marlin F-080 50 ns 63.50 μs

Marlin F-131 25 ns Not applicable

Marlin F-145 50 ns 92.25 μs

Marlin F-146 30 ns 54.78 μs

Marlin F-201 30 ns 64.5 μs

Table 73: Jitter at exposure start (no binning, no sub-sampling)

Note



• Jitter at the beginning of an exposure has no effect on

the length of exposure, i.e. it is always constant.

• By default, the Marlin F-131, the CMOS sensor uses

global shutter, so it cannot be re-triggered until the pre-

vious image has been read out.

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Allied Vision Technologies MF-145B2 Instruction Manual Page 151