Itala | INSTRUCTION MANUAL
matches the configured action command and then generates the trigger. Commands can be sent
in unicast or broadcast mode, depending on whether one or more devices should be triggered.
To improve the synchronism of the trigger on camera the Scheduled Action Commands must be
used (6.12.2).
6.12.2 Scheduled Action Command
Scheduled Action Commands allows a trigger action to be generated on one or more devices at a
specific time in the future, with nanosecond granularity. The only two requirements are enabling
of PTP feature and synchronizing the camera with PTP master clock (see 6.20.1), otherwise the
scheduled action request is not processed.
The block diagram to explain the architecture of the scheduled action control is shown in Fig.71
and it is discussed in detail below.
When the user sends a scheduled action, the camera checks via hardware that the command in-
formation matches the configured action command. Then, if the scheduled action has a time tag
in the past, the action is processed immediately, otherwise is added into the hardware action time
queue; the queue has a depth of 4, so up to 4 scheduled actions can be handled. If the queue is
full, additional commands will be ignored. When the action timestamp becomes less than or equal
to the reference time, it is removed from the queue and an hardware trigger toward the Exposure
Control is asserted.
If the ACK message is requested, the possible status codes are:
• GEV_STATUS_NO_REF_TIME: if the camera has not a reference time synchronized to any
master clock. The scheduled action request is not processed.
• GEV_STATUS_ACTION_LATE: when the camera received a scheduled action command with
time tag in the past (relative to the device timestamp).
• GEV_STATUS_OVERFLOW: if the timestamp queue is full and the camera received an action
command to be scheduled.
A hardware delay, measured when the scheduled action is configured to trigger a sensor exposure
and caused by hardware processing, is removed in the timestamp in order to compensate for it
and improve the accuracy of the trigger time.
If TriggerOverlap is ON, the latency between exposure time and frame transfer is affected by a
higher uncertainty, therefore the jitter on frame acquisition is higher than when TriggerOverlap is
OFF, even if Scheduled Action is used.
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