Allied Vision Alvium Series - Trigger Signal Flow and Latency

288Alvium USB Cameras User Guide V4.6.1
Triggering and timings
Trigger signal flow
Figure 108 shows an ideal diagram for the trigger signal flow. The external signal
can be a physical source, such as light barrier as hardware trigger or a software
trigger. This external signal starts the exposure of a frame. The end of exposure
starts the readout. High levels show the active state of a signal.
Trigger latency
In theory, a trigger creates an immediate response of the camera, depending on
the cable length. In practice, the computer may add a delay that is mostly
unpredictable, especially on Windows systems. In addition, camera electronics and
sensors have a delay.
Rolling shutter (RS) cameras in this document also have exposure delay, depending
on camera settings, see Triggering with rolling shutter cameras on page 289.
Features availability
States shown in the following graphic apply to Alvium USB cameras. Not all of the
corresponding features may be supported. See the Alvium Cameras Features
Reference at www.alliedvision.com/en/support/technical-documentation/
alvium-usb-documentation for details.
Figure 108: Schematic trigger signal flow
Term Description
External signal Electrical trigger signal starting the signal flow
Exposure Active Exposing a frame
Readout Active Reading out a frame (logical state, not a user feature)
Frame Start Trigger Wait Waiting for a trigger
Acquisition Active Enables frame acquisition: Expose, read out data, or wait for triggers.
Table 150: Trigger signal flow terms
i
External signal
džƉŽƐƵƌĞĐƟǀĞ
ZĞĂĚŽƵƚĐƟǀĞ
FrameTriggerWait
ĐƋƵŝƐŝƟŽŶĐƟǀĞ
Frame 1
12
Frame 2
Frame 2
Frame 1