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This example was written to control a stepper motor drive using the digital output lines of a general purpose DAQ device. The example can be used to control any stepper motor drive which uses step/direction control signals with a DAQ card that can output at least three compatible digital signals, including a hardware-timed pulse train.
This example sets up three digital output tasks using the DAQmx API. One digital line is used to enable the stepper motor drive, while the other two select the direction and generate the required step pulse.
LabVIEW 2011 or compatible
NI-DAQmx 9.3.5 or compatible
Compatible DAQ Device (minimum three suitable digital outputs)
Compatible Stepper Motor Drive (using Step/Dir inputs)
Note: Please consult your hardware's specifications or manufacturer to be sure that your DAQ device's digital output lines operate within the voltage and current range specified by your motor drive. It is possible to damage your equipment if used incorrectly.
Steps to Implement or Execute Code
First, select which digital output lines you will be using to generate the required control signals. You must select the line you are using for each signal in the appropriate front panel control. You must also verify the steps/revolution setting of your stepper motor drive and confirm that the 'Step Pulse Train Frequency' control is set accordingly to achieve your desired velocity. This VI will control a stepper drive for constant velocity. For example, if your stepper motor drive is set to use 200 steps/revolution, a setting of 200 in the 'Step Pulse Train Frequency' will correspond to 1 revolution/second or 60 RPM.
After selecting which digital lines are being used for which signals and confirming the desired steps/revolution setting, verify all connections to the stepper drive and run the VI. Clicking the 'Enable Drive' Boolean will enable the stepper motor axis, and toggling the 'Clockwise/Counterclockwise' Boolean will select the direction of motion.
This example does not include support for feedback or velocity profile smoothing. These more advanced features will require additional programming or the use of a dedicated motion controller.
Again, please be careful and consult your device manufacturer if necessary before attempting to use this code.
**This document has been updated to meet the current required format for the NI Code Exchange.**
Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.