Alkeria NECTA Series - Frame Number; Time Stamp; Encoder Position

7. The processing chain 80
Note
Dual-line BW sensors (and color sensors when in Mode 1) expose simultane-
ously the two lines every line-start trigger event (when line delay is disabled).
Thus, LineNumber increments once every two lines.
7.2.2 Frame Number
The FrameNumber eld is a progressive 16-bit unsigned integer.
If the acquisition-start trigger is active (see Section 6.1), the counter is reset at the acquisition startup
and counts from 0 to AcquisitionBurstLength – 1, then starts over; otherwise, the counter cycles
from 0 to 65535, then starts over.
Example Code 7.3 | Enable frame number chunk data eld
device.EnableChunkData = true;
device.EnableChunkDataField(ChunkDataField.FrameNumber);
7.2.3 Time stamp
The TimeStamp is a 16-bit unsigned integer generated from a 1 ms timer and cleared when acquisition
is started. The TimeStamp value is the value of the timer counter, as captured at the rst line-start
trigger event.
Example Code 7.4 | Enable time stamp chunk data eld
device.EnableChunkData = true;
device.EnableChunkDataField(ChunkDataField.FrameTimeStamp);
The TimeStampExponent property sets the resolution of the timestamp counter. This property repre-
sents the unit of time expressed in power of 10, i. e. a value of -3 means 10
-3
= 1 ms.
A list of all possible values for the TimeStampExponent property can be retrieved in the following way:
Example Code 7.5 | Time stamp exponent property
short[] exp = device.GetAvailableTimeStampExponents();
if (Array.Exists(exp, t => t == -2))
device.TimeStampExponent = -2;
7.2.4 Encoder position
The EncoderPosition is a 32-bit unsigned value indicating the position of the encoder as captured
at the line-start trigger event (LineEncoderPositon) or at the rst line-start trigger event of the ac-
quired frame (FrameEncoderPosition).