Configure BreakpointConfigures a position breakpoint on an axis or encoder.
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Operation (Single) selects between single and buffered breakpoint operation. Valid values are SINGLE and BUFFERED operation. | ||||||||||||
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Board ID is a unique number assigned by Measurement & Automation Explorer (MAX) used to send and receive commands and data to or from a specific NI motion controller. | ||||||||||||
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Axis or Encoder is the axis or encoder to control. You can load Breakpoint Position on encoders mapped to axes 1 through 8 or directly on encoders 0x21 through 0x28. | ||||||||||||
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error in (no error) describes error conditions that occur before this VI runs. The default input of this cluster is no error. If an error already occurred, this VI returns the value of error in in error out. The VI runs normally only if no incoming error exists. Otherwise, the VI passes the error in value to error out. The error in cluster contains the following parameters:
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Mode (Absolute) is the breakpoint enable mode.
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Action (No Change) is the action to perform when the breakpoint is reached.
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Bd ID Out is provided for flow control. You can string together NI-Motion VIs by wiring the Bd ID Out terminal of one VI to the Board ID terminal of the next VI. | ||||||||||||
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Resource Output is the Axis, Vector Space, ADC, or Encoder you wired into the VI. Use Resource Output to pass the resource to another VI and/or to display information about the device. | ||||||||||||
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error out contains error information. If error in indicates an error, error out contains the same error information. Otherwise, it describes the error status that this VI produces.
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Using This VI
The Configure Breakpoint VI configures the breakpoint to the appropriate mode, operation, and action. It also defines the action to perform when the breakpoint is reached—leave the breakpoint output unchanged, reset the breakpoint output to low, set the breakpoint output to high, or toggle the state of breakpoint output. Refer to the Synchronization section of the NI-Motion Help for more information about the types of breakpoints you can configure.
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Note For modulo breakpoints, the magnitude of the breakpoint value must be less than the breakpoint modulus. If this range is exceeded, a modal error is generated when you execute the Enable Breakpoint Output VI. |
Enable mode determines how the previously loaded breakpoint position is interpreted. Absolute breakpoints can be anywhere in the 32-bit position range. Relative breakpoints are relative to the instantaneous encoder position when the breakpoint is enabled. Modulo breakpoints are interpreted within the range of the loaded breakpoint modulus. For more information about modulo breakpoints, refer to the Load Breakpoint Modulus VI.
When an enabled breakpoint is reached, a breakpoint event occurs. You can use the Read Breakpoint Status VI to see if a breakpoint has occurred.
A breakpoint event also can cause the state of the corresponding breakpoint output to change. Action On Breakpoint selects whether the output goes low, goes high, toggles state, or does not change when the breakpoint event occurs. If the breakpoint output is presently in the state defined by Action On Breakpoint, it is forced to the opposite state when the breakpoint is enabled. This guarantees that the appropriate transition occurs when the breakpoint is reached.
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Note NI-Motion does not support breakpoint and high-speed capture functionality on an axis when the primary feedback for that axis is used as analog feedback. |
Absolute
This mode is available in both single and buffered operation. The breakpoint position is interpreted with reference to the zero position (origin). This also applies to all the position data in the buffer for buffered operation.
Relative
This mode is available in both single and buffered operation. For single operation, the breakpoint position is interpreted with reference to the encoder position when the breakpoint is enabled. For buffered operation, the first position data is interpreted with reference to the encoder position when the breakpoint is enabled. The subsequent position data is interpreted relative to the previous breakpoint such that:
Breakpoint[0] = Position on enable + Buffer[0]
Breakpoint[n] = Buffer[n–1] + Buffer[n],
where n 
1.
Modulus (7330/40/90)
This mode is available only in single operation. Modulus breakpoint is used to specify multiple breakpoints with a constant distance between them. The breakpoint position is interpreted with the modulus range such that:
Breakpoint[n] = Breakpoint position + (n × Breakpoint modulus),
where n is any integer.
When the breakpoint is enabled, the controller enables the two breakpoints closest to the current position, one in the forward direction, and one in the reverse. After a breakpoint occurs, you can re-enable the next breakpoint without loading a new position.
Periodic (7350)
This mode is available only in single operation. Periodic breakpoint is an enhanced version of modulus breakpoint. The period determines the distance between each breakpoint:
Breakpoint[n] = Breakpoint position + (n × Breakpoint period),
where n is any integer.
When you load a breakpoint position, it is interpreted as the first breakpoint. After this breakpoint has occurred, the breakpoint status is asserted and the subsequent breakpoint is automatically loaded and enabled by the controller.