Configure Stepper Output

NI-Motion Help

Edition Date: August 2012

Part Number: 372134F-01

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Configures the drive mode, output mode, and polarity of a stepper output.

Device Compatibility

DeviceCompatibility
NI 7330
Y
NI 7340
Y
NI 7344
Y
NI 7350
Y
NI PCI-7390
Y

Details

Polarity sets the polarity for the stepper output. Select TRUE (default) for active low. Select FALSE for active high.

When configured as active low, the output is active when there is a low signal on the output pin. Conversely, active high means that the output is active when there is a high signal on the output pin.
Output Mode specifies the mode as Step and Direction or Clockwise/Counterclockwise.
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.
Axis or Stepper Output is the axis or stepper output to configure. When sent to a stepper axis, this VI configures the mapped stepper output. Alternatively, you can execute this VI directly on the stepper output resource.
error in 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:
status is TRUE if an error occurred before this VI was called, or FALSE if not. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code.
code is a number identifying an error or warning. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code. Use the error handler VIs to look up the meaning of this code and display the corresponding error message.
source is a string that indicates the origin of the error, if any. Typically, source is the name of the VI in which the error occurred.
Drive Mode specifies either Open Collector or Totem Pole mode. Drive Mode is available only on the NI 7350 and is not configurable on NI 7330/40/90 motion controllers.
Bd ID Out is provided for flow control. You can string together NI-Motion VIs by wiring the Board ID Out terminal of one VI to the Board ID terminal of the next VI.
Resource 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.
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.

status is TRUE if an error occurred, or FALSE if not. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code.
code is a number identifying an error or warning. If status is TRUE, code is a nonzero error code. If status is FALSE, code is zero or a warning code. Use the error handler VIs to look up the meaning of this code and display the corresponding error message.
source is a string that indicates the origin of the error, if any. Typically, source is the name of the VI in which the error occurred.

Using This VI

Use this VI to configure a stepper output to correctly interface with a stepper driver. NI-Motion supports the two industry standards for stepper control outputs. The most popular mode is Step and Direction, where one output produces the step pulses and the other output produces a direction signal.

In Clockwise and Counterclockwise (CW/CCW) mode, the first output produces pulses when moving forward, or CW, while the second output produces pulses when moving reverse, or CCW.

In either mode, you can set the active polarity with the polarity bit as active low or active high. For example, in Step and Direction mode, the polarity bits determine whether a high direction output is forward or reverse. It also determines the resting states of outputs when they are not pulsing.

The Configure Stepper Output VI is typically called for each stepper axis prior to using the axis. After the modes and polarity are set, they remain in effect until changed. You can execute this VI at any time.

For the NI 7350 controller, you can set the stepper output Drive Mode to Open Collector or Totem Pole. On the NI 7330/40, stepper output is Open Collector and cannot be changed. On the NI PCI-7390, stepper output is isolated so Drive Mode does not apply and cannot be changed. For more information about Open Collector and Totem Pole drive modes, refer to the documentation for your NI 7350 device.

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