NI 5411/5431
Markers

You can specify a marker by giving an offset count (in number of samples) from the start of the waveform specified by the stage. If the offset is out of range of the number of samples in that stage, the marker does not appear at the output. If the waveform loops multiple times in a stage, the marker generates the same number of times.

Note  The marker begins generating on the last sample preceding the specified placement that is evenly divisible by eight and generates for eight Sample clocks. Therefore, the beginning of the marker is always within eight samples of the specified placement.

If you want a marker at an offset of zero from the start of the waveform, the marker is eight samples long beginning with the first sample. A marker at an offset of seven from the start of the waveform is also eight samples long beginning with the first sample, as shown in the following table. A marker at an offset of eight generates at positions 8–15.

Generated Marker Positions

The following figure shows an analog waveform generating at one connector and a marker generating at another I/O connector. Point A shows a marker generated for requested positions 0–7, and point B shows a marker generated for requested positions of 8–15.

Markers as Trigger Outputs

Note  Marker output signals are an important feature for triggering other devices at a specified time while a waveform generation is in progress.

A delay of more than 76 Sample clocks from the external trigger (EXT_TRIG) edge to the analog waveform generation on the output connector exists. Therefore, synchronizing the NI 5411/5431 output signal to other devices with faster and more predictable trigger response times is difficult. For these applications, use the marker from the NI 5411/5431 as the trigger source for the other device. You can use the NI 5411/5431 marker over the RTSI bus, over the PXI trigger lines, or externally over the connector.