4 point leveling bug?

[p8blr]

I have a pneumatically actuated probe, essentially a bltouch, that I don't want deployed during the rapid movement from point to point throughout bed.g. But the G30 command deploys the probe before moving to the probe location, so I customized bed.g so that the probe deploys and retracts in between moves with a manual G1 jog. However, I've noticed that if I jog exactly to the point, the machine will not probe that location. Offsetting by 1mm in X and Y in my G1 makes it work. Is this a bug?

in config.g

M558 P8 C"!0.io8.in" H4 F{global.probeSpeedFast}:{global.probeSpeedSlow} T99999999 R0.5 A{global.probeCycles} S0.03  ; set Z probe type and the dive height + speeds R0.5 b/c probe needs time to deploy without triggering.
G31 P1000 X-47.8 Y15.2 Z4.1                              ; set Z probe trigger value, offset and trigger height for 1mm nozzle
M557 X47.8:1160.2 Y15.2:1179.8 P21:21                    ; define mesh grid

bed.g

; bed.g
; called to perform automatic bed compensation via G32

M561 ; clear any bed transform

; 4-point bed leveling

M98 P"0:/sys/condHomeAll.g"		; home
G1 Z10 F200                     ; get close to bed

G4 S.5							; wait
M106 P2 S255 				    ; turn on fan to clean bed
M402
G1 X1082.8 Y135.8 F10000		; move to first point with offset
M401
G30 P0 X1034 Y150 Z-99999		; probe front right z1
M402
G1 X1082.8 Y1010.8 F10000		; move to second point with offset
M401
G30 P1 X1034 Y1025 Z-99999		; probe back right z2
M402
G1 X198.8 Y1010.8 F10000		; move to third point with offset
M401
G30 P2 X150 Y1025 Z-99999		; probe back left z3
M402
G1 X198.8 Y135.8 F10000			; move to fourth point with offset
M401
G30 P3 X150 Y150 Z-99999 S4	    ; probe front left z4
M402
M106 P2 S0  				    ; turn off fan to clean bed

In short, G30 X10 Y10 will not probe if the probe is already over X10 Y10. For Example, if the probe offset is X-5 Y-5 and the nozzle is at X15 Y15, the probe will already be at X10 Y10 so a G30 X10 Y10 will fail to probe.

[Phaedrux]

Which Duet board and firmware version?

[p8blr]

@Phaedrux Previously I was on 3.4.6, but I've upgraded to 3.5.0 RC1 and have the same issue. I'm running a Duet 6XD, (4) 3HC, (2) 1XD, running in SBC mode with an 8GB Raspberry Pi 4 with the Lite version of the image.

[dc42]

@p8blr if your probe has similar deploy/retract requirements to BLTouch then you may be better off using P9 in your M558 command instead of P8.

[p8blr]

@dc42 You actually recommended I use a type 8 in another forum post because M401 and M402 weren't working properly.

https://forum.duet3d.com/topic/31077/pneumatic-probe?_=1695134579442

Thanks