Balluff MATRIX VISION mvBlueNAOS, Technical Manual

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1.18 Use Cases 197
An example of the chunk data attached to the image can be seen below. The timestamp is in µs and Counter1
counts the reset pulses, in this case itself generated by the camera via Timer1 .
Figure 3: ChunkData
The task of resetting the counter at the beginning of the acquisition can be done by setting the reset property
accordingly. Of course is this all independent whether the camera is acquiring images in triggered or continuous
mode.
1.18.6.3.4 Synchronizing using a pulse-per-second signal
In order to eliminate the unknown drifts of different devices, a PPS (pulse per second) signal can be fed into each
camera using a PC with NTP (network time protocol software), GPS devices or even a looped-back camera timer.
From these pulses the device can extract how long one second is . When a device detects that it is no longer running
precisely it will adapt its internal clock leading to a "stabilized oscillator".
The device would then maintain their timestamp-differences over long times and stay synchronized. The initial
difference between the timers - before the PPS was used - remains however. If you aim to eliminate that as well,
you can use the
mvTimestampReset
up front with the same PPS input signal. In an application this can be
configured like this (C# syntax):
// --------------------------------------------------------------------------
bool waitForNextPulse(Device pDev, String triggerLine)
// --------------------------------------------------------------------------
{
GenICam.CounterAndTimerControl ctc = new GenICam.CounterAndTimerControl(pDev);
ctc.counterEventSource.writeS(triggerLine);
long momentaryValue = ctc.counterValue.read();
for (int i=0; i<12; i++)
{
System.Threading.Thread.Sleep(100);
if (momentaryValue != ctc.counterValue.read())
{
return true;
}
}
return false;
}
// --------------------------------------------------------------------------
void SetupPPS(Device[] pDevs)
// --------------------------------------------------------------------------
{
string TriggerLine = "Line4";
if (!waitForNextPulse(pDevs[0],TriggerLine))
{
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