[OpenPnP] Home position, endstop, 0.0.0 coordinate ..

[manu f]

Hello,

this is a basic newby question, I search but not sure to undertand all..this stay confuse for me..

I understand that OpenPnP uses the right handed coordinate.

Ok, but where the 0.0.0 coordinate must be ? at top right corner and Z at top?

Actualy, I set my smoothiware to use endstop switch for homing ($H) and there are positionning a top right corner and at top for Z and set all axis coordinate to 0 (so top right corner and Z at top = (0.0.0).

Subsidiary question: I saw in the machine.xml I got as example support, that HOME_COMMAND use G28.

I understand that G28 use arbitrary position set by G28.1 as home position.

but if I right understand G28 could be use only if a endstop homing position is done before ($H).. So what is correct gcode sentenses for HOME_COMMAND ?

$H and after use G28 if we need a different "home" position than the 0.0.0 position?

In fact I think I confuse the "home" position who is an arbitrary position and the initial homing with endstop switch who set axis to 0.0.0 position..

Somebody could clarify please ?

[ma...@makr.zone]

Hi manu,

Strictly speaking, the absolute coordinate system (where it is zero) doesn't matter, only the orientation is important:

https://github.com/openpnp/openpnp/wiki/Machine-Axes#the-openpnp-coordinate-system

But as a convention, users have their X0, Y0 near the front, left corner.

They have Z0 where a single nozzle is fully retracted, or the at the balance-point with two nozzles. Z then goes into the negative, down to the table. This is also the safest to setup, otherwise you have to be careful to set the right Safe Z and any Z coordinates which are typically initialized to 0 before you overwrite/capture them.

> I saw in the machine.xml I got as example support, that HOME_COMMAND use G28.

The $H vs. G28 confusion is due to the CNC=1 define you used for your firmware compilation (Grbl-mode).

https://smoothieware.org/grbl-mode?s[]=grbl&s[]=mode

Traditionally, OpenPnP users have used it without the CNC switch set, so you will find a lot of documentation and example machine.xml with G28 instead of $H.

Issues & Solutions should automatically recognize the Grbl-mode from M115 and adapt the proposed G-code. Grbl-mode may not have been as extensively tested. though.

> after use G28 if we need a different "home" position than the 0.0.0 position?

Frankly I don't know much about Grbl-mode. AFAIK what you ask for (single axes homing) is not fully documented in the G-codes. You can read the source code to figure it out (I did that when I wrote I&S support, but I don't remember). Or you can switch the Grbl-mode off by recompiling without CNC=1.

> In fact I think I confuse the "home" position who is an arbitrary position and the initial homing with endstop switch who set axis to 0.0.0 position..

I don't understand what you mean here.

_Mark

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[manu f]

@ma...@makr.zone 

So, Mark to be sure I understood, openpnp user by convention use this setting for home (0,0) on X,Y:

                X

- ------------------------------ +

|                                   |  +

|                                   | 

|                                   |    Y      (top view)

|                                   |

|                                   | -

0 -------------------------------

Home

About M115, Issue and solution look like not recognize M115 cause it didn't populate Gcode..

Here what I got from pronterface:

SENDING:M115
FIRMWARE_NAME:Smoothieware, FIRMWARE_URL:http%3A//smoothieware.org, X-SOURCE_CODE_URL:https%3A//github.com/markmaker/Smoothieware/tree/feature/best-for-pnp, FIRMWARE_VERSION:~11myvar2, X-FIRMWARE_BUILD_DATE:Aug 13 2021 20:29:42, X-SYSTEM_CLOCK:100MHz, X-AXES:5, X-PAXES:5, X-GRBL_MODE:1, X-CNC:1, X-MSD:1, X-WARNING:deprecated_MCU

Do it look like correct Mark ?

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/e4f00985-31f0-c827-7d3b-4c7bc2049ac3%40makr.zone.