Breakpoint
Position breakpoints are an enhancement to the encoder decoders on the NI motion controller and are available when the encoders operate as axis feedback or as independent encoder resources. Breakpoint functionality is available on servo and closed-loop stepper axes. You can use Breakpoint functions to configure, enable, and read the position breakpoint status. Advanced functions, such as periodic breakpoint and buffered breakpoint can be used to achieve higher-frequency breakpoints. Refer to Buffered Operations Functions to configure buffers for buffered breakpoints. You also can load a breakpoint position modulus. Like all motion I/O, breakpoint outputs also can function as general-purpose outputs with the Set Breakpoint Output MOMO function.
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Note All breakpoints can be affected by jitter in the motion system. For example, if you have breakpoint positions very close to each other, the jitter in the motion system could cause the position to change enough to reach the breakpoint when a breakpoint is not intended. Increase the value of the breakpoint window using Set u32 to compensate for system jitter. |
Refer to the following table for the maximum breakpoint rates for each type of breakpoint. Not all breakpoints are available on all controllers.
| Breakpoint Type | Maximum Frequency |
|---|---|
| Single | 150 Hz |
| Buffered, PID rate of 62.5 µs to 250 µs |
2 kHz |
| Buffered, PID rate greater than 250 µs |
1 kHz |
| Periodic | 4 MHz |