Synchronization

You can synchronize NI motion controllers with NI data and image acquisition devices using breakpoints and high-speed captures. The following figure illustrates an expanded view of the topics covered in this section.

* Breakpoints cause a digital output to change state when a specified position is reached by an encoder. Breakpoints are not supported by the NI SoftMotion Controller.

** A high-speed capture records the position of an encoder when a digital line is used as a trigger. High-speed captures are not supported by the NI SoftMotion Controller.

Note  If you are using RTSI to connect your motion controller to a National Instruments data or image acquisition device, be aware that the NI SoftMotion Controller does not support RTSI.

Timing and triggering with NI-Motion is always related to either position or velocity. Synchronizing position and velocity information with the external world allows you to coordinate measurements with moves. You can program the motion controller to trigger another device at specified positions using RTSI or a pin on the Motion I/O connector. This functionality is called breakpoints, which are divided into absolute breakpoints, relative position breakpoints, and periodically occurring breakpoints.

In some cases, it may be necessary to synchronize position with some measurement occurring external to the motion controller. For example, you might be aligning two fiber optic cables, in which case the maximum optical power needs to correspond with the alignment position. To align the fibers, the external device that is recording the optical power must trigger the motion controller so that positions and optical power measurements can be synchronized and analyzed. This functionality is known as high-speed capture or trigger inputs. The motion controller can be triggered by another device using RTSI or externally using a pin on the Motion I/O connector. When triggered, the motion controller can latch the current position of the encoder, which can be read and recorded.

The following table shows the availability of breakpoint modes on each NI motion controller.

Breakpoint Mode	NI 7350	NI 7340, NI 7330, and NI 7390
Absolute*	Y	Y
Relative*	Y	Y
Periodic	Y	N
Modulus	N	Y
Buffered	Y	N
* Available in buffered and single operation for NI 7350 and in single operation only for all other controllers