Min spindle speed $31 is ignored (MKS DLC32)

LightBurn Hardware Compatibility
1

For those who are using an MKS DLC32, is anyone else having an issue with $31 not being honored?
I have $30 set at 1000.
I have gone so far as setting $31 to 1000 and it still ramps the laser all the way to 0 at the beginning and ends of cuts/engravings.
Any setting for $31 appears to be ignored.

This is for a CO2 laser, so I need a way to set a minimum power output.
I’m running V2.10_H35_2022_0621_N_ZX_001 because my laser has a Z axis, I require a persistently stored G10 L2 P1 X-600 Y-400, and I need a functioning $HZ command. The other firmware versions don’t support all these requirements. I’m considering switching to FluidNC, but I’m holding back as I would like to keep the display working.

The core issue that I’m trying to resolve are small gaps at the beginning and ends of engravings. It’s my understanding that $31 is the place to tune this, but please tell me otherwise, if I’m wrong. Thanks!

2

Here’s the settings and a photo of the results of the attached gcode. This is with $31 being set at a full 1000! Any other value makes no difference.

$I
[VER:1.1h.2020062101:]
[OPT:MPHSW]
[MSG:Using machine:MKS DLC32]
[MSG:Mode=AP:SSDI=MKS_DLC_CS53373:IP=192.168.4.1:MAC=E8-31-CD-5B-7D-D1]
ok
$$
$0=10
$1=25
$2=0
$3=0
$4=0
$5=1
$6=0
$10=2
$11=0.010
$12=0.002
$13=0
$20=0
$21=1
$22=1
$23=0
$24=300.000
$25=1200.000
$26=250.000
$27=10.000
$28=20000.000
$30=1000.000
$31=1000.000
$32=1
$38=1
$40=1
$100=39.551
$101=78.986
$102=795.899
$103=100.000
$104=100.000
$105=100.000
$110=100000.000
$111=100000.000
$112=200.000
$113=1000.000
$114=1000.000
$115=1000.000
$120=450.000
$121=300.000
$122=5.000
$123=200.000
$124=200.000
$125=200.000
$130=700.000
$131=500.000
$132=142.000
$133=300.000
$134=300.000
$135=300.000
ok

; LightBurn 1.7.04
; GRBL device profile, current position
; Bounds: X-25.4 Y-25.4 to X0 Y0

;USER START SCRIPT
M7
;USER START SCRIPT

G00 G17 G40 G21 G54
G91
M4
; Cut @ 80 mm/sec, 30% power
M7
G0 X0Y-25.4
G4 P0.35
; Layer C02
G1 X-25.4S300F4800
G1 Y25.4
G1 X25.4
G1 Y-25.4
G0
G4 P0.35
M9
G1 S0
M5
; return to starting pos
G0 X0Y25.4

;USER END SCRIPT
M9
;USER END SCRIPT
M2

example square
example square1361×1185 178 KB

3

I have the same controller but in laser diode, not in CO2.
If you find it useful, I can see the settings later that I have on mine.
However, there is this software support that I don’t know if it helps.