Auto Bed Leveling (ABL) issues on G2S Pro

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Auto Bed Leveling (ABL) issues on G2S Pro

Post by aleXall » Fri Dec 30, 2016 2:47 am

The following message occurs on Repetier msg board, when G29 command run by gcode

Code: Select all

G29 Auto Bed Leveling
?Probe  position out of range.
?Probe  position out of range.
Instead when I send manually G28 G29 sequence, it works :shock:
I've tried also to move G28 G29 lines up or down at start of gcode, with no results.

By intuition placed G4 command before and after G29 and now it works!! :mrgreen:
In Slic3r/Printer Settings/Custom gcode/Start g-code textbox I've placed the following code

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G28 ; home all axes
G4 P500 ;PAUSE 500ms to prevent ABL failure - motherboard need time to understand :D
G29; Auto-calibration
G4 P100 ;PAUSE 100ms to prevent ABL failure - G0 G1 codes after G29 make it failure!
G0 Z50 F3000 ; lift nozzle

All problems seemed solved... But no!! :evil: With ABL functioning correctly now,
prints are not parallel to bed, but slanted so that it adheres only to one side :(
Are there any solutions?

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Re: Auto Bed Leveling (ABL) issues on G2S Pro

Post by dohabandit » Sat Aug 25, 2018 9:49 am

Has anyone here tried replacing the ABL probe with an inductive type probe?

I ordered a 4mm type and will be attempting to get it installed shortly. The metal springloaded probe was binding up and very unreliable. I am giving up on the stock probe.

This new probe requires 12v, so I am wondering which route to go:
1) Use two resistors to make a voltage divider and get the voltage down to 5v for the uCPU input pins (really don't want to fry my GT2650 board).
2) Use a diode and internal pullup setting. The diode basically lets the input "float" when the inductive sensor would normally close and supply +12v which the diode blocks. Combined with internal pullup setting on the probe input, it goes high to 5v and is read as a high. Otherwise, the input pin is pulled to GND by the inductive sensor and that reads as a LOW. Question is, where do I enable the internal pull up resistor setting in the Marlin firmware? Is this even supported by the GT2650 board? (not all GPIO pins support settable pull-up or pull-down resistors) I will freely admit I don't know a lot about the GT2650 board and the microcontroller it is based on. Will be doing some research soon though because I have already ordered the inductive sensor.

My brother has a $80k CNC machine in his metal fab shop. Once I get this figured out, I will likely have some aluminum cut on his CNC that allows me to mount both the J head and inductive sensor in the center of the spider. I will upload some pics as it progresses. I have seen someone else has a design printed in PLA on thingiverse, but in my experience with the J head and PLA mount, I would rather have a piece of aluminum doing the job.

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Re: Auto Bed Leveling (ABL) issues on G2S Pro

Post by _kaktus_ » Sat Aug 25, 2018 1:15 pm


Your solutions sound sensible. ;)

If you fail to switch on the internal Pull-up resistor at the µC input, you can always use an external resistor.
Remember that µC pins can be pulled up to a maximum supply voltage of µC.
When you don't want high pull-up or pull-down current, a reasonable resistor value is 10kΩ.

It is worth to check if the supply voltage µC in your controller is not 3V3.
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