Hi,
I am trying to set up a 3d print head on the UR3. Firstly the print head uses a stepper motor to extrude. I have decided to use STEP/DIR mode to control the motor. Should I connect the 3 pins as Tool I/O digital outputs or general I/O digital outputs on the UR controller?
Also, can I utilize the internal the different voltage levels of tool digital output directly when I connect to the stepper motor driver?
Thanks in advance
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First off; are you sure the stepper driver accepts 24V on STEP/DIR? The stepepr drivers I have worked with for 3D printing are all 5V. 
Tool I/O are signals coming from the small connector on the tool mounting flange at the end of the robot arm.
The other I/O are signals inside the control box.
I don’t quite understand your last question. Do you want to power the stepper motor from the Tool I/O?
The controller I have is a bigtreetech controller board with in inbuilt voltage regulators to step it down to 12v.5v and 3.3v. So that should not be a problem.
To your final comment, yes that’s what I would like to know. For such a case is it better to use Tool I/O or general configurable I/O?
The reason I ask is, when I try to use SET command on UR script to set some action, the tool_output[0],[1] are not getting displayed, only normal digital outputs are shown. Is that normal?
The Tool I/O can “only” supply 600mA (or 1200mA for e-series robots). So that depends on the power usage of your stepper motor.
I/O in the controller has 2A from the internal supply.
I’m not sure what you mean by the outputs not display in UR script. Can you take a picture/screenshot?
These are the only options. So I am unable to set actions/tasks of the stepper motor when I use Tool I/O.
It’s most likely due to a wrong Tool I/O setup. Check that Standard Output is enabled and Dual Pin Power is disabled.
Also make sure you choose either PNP or NPN depending on your setup. Knowing the 3D printer world, you would want PNP.
EDIT: Also remember to set a voltage at Tool Output Voltage.
All the options are as you have shown but still not able to select the required tool I/O. I am unsure what the exact problem is…
Thank you
When we configure in the Installation tab, I had configured the tool I/O such that its High when running and low when stopped. Do you think that is needed or can I remove those configs and run them from commands?
Thank you
That’s your “issue” then. If you telling the output to be “high when running”, you won’t have any control over it. You can set it to “low when not running” only, and it will turn off the signal in case the robot stops unintentionally. And then you will have control over the input.
Yeah, thank you for the clarification! I understand it now.