I'll see if I can borrow a scope. Thanks all

@oliof Tested at 100,200,500. I see no significant difference. I removed the inverted ! in the M452 just for testing. At S245 HZ is stable. at S246 the HZ starts out momentarily at requested frequency but then varies between 60hz and requested. At S248 there is no HZ. With the ! inverter the Number is around 20 for the "S" The voltage does change with "S" changing. Full range. Does the Laser need the HZ? Has anyone else tested for HZ?

Unit is a Duet 2 wifi firmware 3.4.2.
M452 C"exp.heater4" R250 F2000
I'm in experimental stage. With a Fluke 76 meter set to HZ I will read Frequency if my command line is G1 X50 S200 F100. If the "S" is set above 240 or below 15 I will read a voltage but no frequency. I have voltage readings all the time. Voltage varies "S". I have also test this on Bigtreetech BTT E3 RRF. The min and max numbers are little different but not by much. The output voltage can't see max if it's lower. I have not hooked up to laser yet and/or tried to create a file. Is this acceptable or is there a way to get full range frequency? Can laser application put limits on "S" range?

@cubex249
I figured it out. I added a I1 in the M558

Installing a Orion Piezo on a cubex. The Z probe is always at 1000 with or without piezo connected to probe header. When connected and i touch the end of the hot end the blue light flashes and Z probe goes to zero. in this configuration I get a error that the Z home signal is on before homing starts. I'm configuring this thru the RepRap configuration software. I've also have left the configuration to z probe and then used a n/c switch but it start to home but i can't stop it. the blue led flashes when I tap the hot end but it doesn't stop. The following moves x,y to 25mm z retracts (30mm?) and then I get the error. Thank You for your help. I'm about as new as one can get to this.

G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves

; Network
M550 P"Cubex" ; Set machine name
M552 S1 ; Enable network
;*** Access point is configured manually via M587
M586 P0 S1 ; Enable HTTP
M586 P1 S0 ; Disable FTP
M586 P2 S0 ; Disable Telnet

; Drives
M569 P0 S0 ; Physical drive 0 goes backwards
M569 P1 S0 ; Physical drive 1 goes backwards
M569 P2 S1 ; Physical drive 2 goes forwards
M569 P3 S1 ; Physical drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
M92 X80.00 Y80.00 Z4000.00 E420.00 ; Set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00 ; Set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00 ; Set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00 ; Set accelerations (mm/s^2)
M906 X800.00 Y800.00 Z800.00 E800.00 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X25 Y10 Z0 S1 ; Set axis minima
M208 X250 Y250 Z220 S0 ; Set axis maxima

; Endstops
M574 X1 Y1 S0 ; Set active low and disabled endstops

; Z-Probe
M574 Z1 S2 ; Set endstops controlled by probe
M558 P5 R0.4 H5 F1200 T6000 ; Set Z probe type to effector and the dive height + speeds
G31 P500 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height
M557 X25:25 Y25:195 S20 ; Define mesh grid

; Heaters
M140 H-1 ; Disable heated bed
M305 P1 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 1
M143 H1 S280 ; Set temperature limit for heater 1 to 280C

; Fans
M106 P0 S1 I0 F500 H-1 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H-1 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned off

; Tools
M563 P0 D0 H1 ; Define tool 0
G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C

; Automatic power saving
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; Set voltage thresholds and actions to run on power loss

; Custom settings are not configured

; homez.g
; called to home the Z axis
;
; generated by RepRapFirmware Configuration Tool v2 on Tue May 21 2019 15:52:37 GMT-0400 (Eastern Daylight Time)
G91 ; relative positioning
G1 Z5 F6000 S2 ; lift Z relative to current position
G90 ; absolute positioning
G1 X25 Y25 F6000 ; go to first probe point
G30 ; home Z by probing the bed

; Uncomment the following lines to lift Z after probing
;G91 ; relative positioning
;G1 S2 Z5 F100 ; lift Z relative to current position
;G90 ; absolute positioning