Spindle setup

Hi everyone,
this is my first post here and pleased to see some nice and vibrant community around open source project like this one.
Recently we purchased well built CNC Milling machine. It has MTs 107 drivers and IO3-R2 BOB. Since we didnt have enough money for proper spindle we decided to go with mounted handheld router. Its connected to the BOB (just power cable)  so one can turn it on and off and spindle speed is set by hand on the router itself (it has speed marks 1,2,3 ... ) . 
Also, BOB is connected trough LPT port thus I used StepConf to set everything up. Router power  is connected to Pin 1, and I put spindle PWM there, and later I choose PWM 0 Hz to use PDM mode. 
Now, when I start Axis UI, spindle starts right away so I had to press + sign few times in order to stop it (on a spindle display when it hits 1500 RPM mark it stops spinning). Also, everytime my machine hits limit switch on any axis spindle starts spinning. I assume this is not expected behaviour. Also, I tried PWM mode with 30Hz which also set another problems. 
As far as I understood, there are few ways to setup spindle in linuxcnc but since I'm new to this I get a feeling that what I did is not the proper way to setup this part of the linuxcnc software considering my current setup.
If anyone has and idea what I did wrong or how to setup spindle please let me know.
Thanks in advance

Thank you Tommy,
I did try that before but the problem is that spindle don't start when I execute g-code. I have to press + sign until it reaches 1500 on the spindle display and then it starts. If I start g-code without starting the spindle it does not start on g-code start and if I start spindle before g-code start then g-code start executing and turn off the spindle.
Thanks again for your help.

Upload your configuration files and sample G-code program

 Hi, sorry for late reply.
My confing files:
 
  

my g-code start:; GCODE Generated by cam.openbuilds.com on 2023-12-28
G21 ; mm-mode
; Operation 0: CNC: Vector (path inside)
; Endmill Diameter: 6

G0 Z24; move to z-safe height
G0 F1000 X72.0293 Y37.5218

G0 Z0
G1 F20 Z-1.0000
G1 F200 X71.9918 Y38.2125 Z-1.0000 S1
G1 F200 X72.1136 Y38.8934 Z-1.0000 S1
G1 F200 X72.3880 Y39.5283 Z-1.0000 S1
G1 F200 X72.8680 Y40.1529 Z-1.0000 S1
G1 F200 X93.4320 Y60.6563 Z-1.0000 S1
G1 F200 X64.9452 Y64.9073 Z-1.0000 S1
G1 F200 X64.2775 Y65.0875 Z-1.0000 S1
G1 F200 X63.6687 Y65.4159 Z-1.0000 S1
 

I will try this same code and insert M3 s24000 at the code start and post results.
Thank you very much for all the help.

Thank you Tommy,
what you said did the trick and it works flawlessly.
One more thing if you can answer me. While in Stepconf, when I reach to page with Spindle setup, I choose 0Hz to enter PDM mode. There are few settings there like: Speed 1, Speed 2, PWM 1 and PWM 2. If I change PWM1 from 0.1 to 0.4 then in Axis UI when I type G0 Z10 for example, it does not travel 10mm thus I have to change PWM1 and PWM2 until I find exact ratio. Why is that?
Many thanks