It is a 16Gb formatted in FAT32

Thanks, it is Nema 42... Data sheet said 6A

The datasheet of external driver said :
For reliable response, the pulse width should be greater than 2.5μs
On the 1XD board, does it means the M569 T parameter is automatically set to 2.7µs ?
In that case it should work no ? or do I have to setup M569 T2.5 ?

In fact I made tests on my development machine because a customer already has a big machine with external stepper drivers that's run with Repetier firmware and he though to switch to Duet3 and RRF3. As the Motors need 6A and more and brakes (like in my development machine). It is not possible to use the Duet3 drivers.
You think there is no possibility to use external drivers for Z and ZProbe ?

Yes the brakes are normally engaged and we supply power for release them

The problem with this configuration is :
Z motors needs brakes, it works fine in normal use. But if I push Emergency Stop button, the bed goes down quickly...
Is there a way to activate brakes when pushing Emergency Stop button ? (before doing the Emergency Stop ?)

100 probe points works too...

I made an other test :
Connect the 2 Z-motors to the drivers of the 6HC board, and changing only the configuration of the Z stepper motors... (No change in the others parameters of config.g)
Z probing works fine ! no error, bed is fully probed

Increased dive height to 15mm > the G29 fails on the twelfth probe
(Z motors on the 1XD, and ZProbe on the 6HC)

@dc42
I do not see or hear any Z skipping steps, Z movements are smooth and regular.

@dc42

Thanks, I will try to increase dive height, just for summarize :

1 - The Z Motors are connected on the 1XD board with 2 external drivers
https://www.omc-stepperonline.com/download/DM556N-L.pdf

If I connect the Probe on the 1XD board :

• The signal is OK on the G30 probe
• The signal is OK on the first G29 probe, then wrong on the second probe

If I connect the Probe on the 6HC board :

• The signal is OK on the G30 probe
• The signal is OK on the first G29 probe, then reduce on other probes and after about 10-15 probe the signal is wrong.

2 - If I connect the Z Motors and Z Probe on the 6HC (Same dive height), ZProbe works (but I have other problems with brakes of Z motors)

I have checked manually the bed level (in case of the bed was too much inclinated), it is at about 0.3mm error.

I have also checked the probe sensor by sending M401/M402 at 100ms delay, it looks OK !

I'm confounded, any idea or thing to test ??