I think a flow sensor and a thermistor would be the best solution, if any of them are triggered the laser should be pause the job.

Same for the lid switch.

@dc42 many thank's!

I add this line in my config.g

; Set Cartesian type and segment interval one second and length 3mm
M669 K0 S1 T3

In the middle of a 200mm straight cut the pause will be done within the second and move set with M669

So this works and I will add this line to my CNC too, btw. I do not see any slowness in normal cut and engrave jobs too.

@cosmowave I use your script above with some slightly modification and now it works so far

var counter=0
var sum=0

while true
  G4 S2
  if job.duration = null
      ; No job ignore sensor reading
  else
      ; Check Water Flow
      if var.counter < 10
        set var.sum = {var.sum + fans[0].rpm}
        set var.counter = var.counter + 1
      else 
        if {var.sum / var.counter} < 50
          ; NO FLOW
          var.counter = 0
          var.sum = 0
          M25
          M118 S"No Water flow!" 
      
      ; Check water temperature
      if sensors.analog[0].lastReading > 35
         M25
         M118 S"Water to hot!"

@dc42 many thank's!

I add this line in my config.g

; Set Cartesian type and segment interval one second and length 3mm
M669 K0 S1 T3

In the middle of a 200mm straight cut the pause will be done within the second and move set with M669

So this works and I will add this line to my CNC too, btw. I do not see any slowness in normal cut and engrave jobs too.

@dc42 said in Connect a water flow sensor --> will M591 P7 work in Laser mode?:

16/3 revs/sec = 320 rpm.

Many thank's!

@dc42 but there is no example how the array variable type could be used in scripts I found. Maybe you are so kind and add something in the wiki or here.

Many thank's in advance!

@owend @Print3d

Since RRF 3.3beta2 there are arrays and objects supported:
https://duet3d.dozuki.com/Wiki/GCode_Meta_Commands#Section_Types

@cosmowave there is still an issue, the sum value will get higher and higher, so when the flow sensor will return only zero after an hour it takes several runs to get the avg town to trigger the alarm.

var val1 = 0
var val2 = 0
var val3 = 0
var val4 = 0
var val5 = 0
var max= 5
var avg = 0
var pos = 1
var initDone = 0
while true
  G4 S2 ; run every two seconds
  if pos = 1
    set val1 = fans[0].rpm
  if pos = 2
    set val2 = fans[0].rpm
  if pos = 3
    set val3 = fans[0].rpm
  if pos = 4
    set val4 = fans[0].rpm
  if pos = 5
    set val5 = fans[0].rpm
 set  pos = pos +1 
  if pos > max
    set pos = 1
    if initDone = 0
      set initDone = 1
  set avg = {val1 + val2 + val3 + val4 + val5} / max

  if initDone > 0
    if avg < 50
       M118 S"no water flow"
       M25

This code is not tested jet and far from nice...

@cosmowave You add the current value to the sum variable all the time --> so after 100 readings you got the sum of them and calculate the average by the dvision of 100 reading, so the avg value gets higher and higher.

@cosmowave this will not work because as more readings the sum gets as less the chance that the avg value comes close to the low value.

There should be something like a array with 10 values which are overwritten every 10 readings to get an reliable value.

@cosmowave so create 10 position variables and one counter and avg or is there a type of list /array available too?
How to create such a script that it uses as less ressources of the system as posible?

There is an variable type of array but I have no clue how to assign a value or sum the values to get an AVG with the informations provided there.

@o_lampe RRF knows the start and target point with the path and speed it moves so it should not be rocket science to calculate the position where it is at any time.