Additional Documentation for LabView Marlin Driver

Creality Ender 3

These are the settings and parameters for the Creality Ender 3 3D printer.

Also here are brief descriptions and notes for the Instrument Driver sub VI's.

Serial Port Settings

These are the default serial port settings that the printer needs to communicate. If for whatever reason these settings are changed in your LabVIEW program, revert them back to these.

Baud rate: 115200

Flow Control: none

Parity: none

Data Bits: 8

Stop Bits: 1

Printer Specs

Position Range

X:0-235mm

Y:0-235mm

Z:0-250mm

Step Size

Full Step Size:

X: 0.2 mm

Y: 0.2 mm

Z: 0.04 mm (not verified yet)

Micro Step Size:

X: 0.0125 mm

Y: 0.0125 mm

Z: 0.0025 mm (not verified yet, sometimes the z axis disables microstepping because of limited torque during microstepping)

The stepper motor drivers have feature called microstepping where the driver can hold the motor between two of the physical steps in the stepper motor by partially powering each of the two phases. This feature has some advantages and drawbacks.

Advantage: Microstepping reduces vibrations during motion, making the velocity of the head during movement closer to constant.

Disadvantage: If you stop the head at one of these microsteps between the actual physical steps, the accuracy of your position is significantly reduced. Microsteps are not necessary equal in size, so the position the head has stopped at doesn't correspond to the number of steps times the step size.

It's recommended to move the head in full step increments if positional accuracy is important in your measurement.

Step Rates

Velocity:

X: >10,000 mm/min

Y: >10,000 mm/min

Z: 300 mm/min

Acceleration:

X: 30,000 mm/min^2

Y: 30,000 mm/min^2

Z: 3,000 mm/min^2

Instrument Driver Sub VI's

Initialize

Description:

Use this to establish the serial connection to the 3D printer. This should be called before any other Instrument Driver VI's.

Action Auto Home

Description:

Tells the 3D printer to Auto Home, which will establish the (0,0,0) coordinate at the end stops.

Use this on startup (after the Initialize VI) to ensure the printer won't try and move the head past the bounds.

Notes:

Sends the G28 command and then runs the Data Read Position VI)

Action Step

Description:

Moves the head a step in the X, Y, or Z axis. The user specifies axis, direction on axis, step distance, and speed of movement.

Notes:

Please be careful if you have attached an instrument that may get caught on things. Crashing your instrument is hazardous for the instrument and the printer.

The current position of the head is required for this VI to function because G-code command used within this VI moves the head to a specific position. To determine the specific position the head must move to, the current position is needed.

Steps the head in the desired axis. Choose, axis (X,Y,Z), direction, (positive or negative), step size, and speed)

Action G Code Command

Description:

Allows users to enter an arbitrary G-Code command. See the G-Code Introduction page for help.

Notes:

This VI does not support reading G-Code or M-Code

Please be careful what commands you use; it is possible to damage the printer if you're not careful.

Data Read Position

Description

Reads the current position of the head.

Notes:

Writes the M114 command and then reads the read buffer until the position is stated.

Close

Description

Closes the serial connection.

Notes:

It's recommended to include this at the end of your program, otherwise the serial connection is maintained and other applications can't connect to the printer.

Recommendations

For best position accuracy, use full steps, 0.2 mm for X and Y, 0.04 mm for Z.

To minimized position error from backlash hysteresis, always step in the same direction for measurements. If you took your measurements moving the head in the positive direction and you need to go in the negative direction for your next measurement, move the head past the point and then go forward to the desired position.

Alternatively, backlash can be reduced by making sure the X and Y belts are tight.

BE VERY CAREFUL NOT TO CRASH THE HEAD!!!

If you have an instrument attached that sticks out, make sure any movement command you send to the printer won't crash your instrument into anything. This can damage your instrument and the printer.