What would it be?
These 8 bit machines are plenty fast for most printers.
Seems like many of these they handle like a printer… Wonder if they have a specific driver for it…
they were often used as GPIO pins wiggling independent pins. For example CNCs had step/direction pin pairs for 3 axis plus an enable pin and inputs for endstops and e-stop.
I put an Arduino running GRBL on the parallel port of a CNC I have and that turned it into a USB compatible system. Something like this could be done with the machine in question if we knew what the parallel port signal names were.
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Rather than trying to resurrect this connection logic, converting to one of the current controllers would seem to be a better use of time… its not that difficult 
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You are probably correct, but $<20 I’d try it and see what happened… it’s relatively low cost and if it’s a normal parallel port, you might have success…
I still follow the KISS principle… low cost to check… could be a total loss of 20 bucks or it could work …
It would still be worth having the machine, even if you had to gut the electronics…
Speaking again as someone who has written and maintained a parallel port driver, it looks like a waste of time and $20.
That’s very possible…
So you think that I should install the M2 NANO board I have spare?
Current plug has 5 ports and M2 has 4 so I would need to change the plug, how would I know which wire goes where?
I really like tinkering but unsure on what exactly I need to do here to get this unit up and running. If I need to use different software that’s not a problem as that is easily sorted out.
Thank you all for your input, appreciate it.
That would be the least costly option.
If I were you I would:
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First draw a schematic of what you have including enumerating what voltages are present on supply connections. You can use the schematic I provided below as a starting point. Use a DVM to make voltage and continuity measurements. This painstaking activity will save you a lot of grief as you start the conversion.
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Then post it here and we can review it.
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Draw up another schematic adding the M2. Show remove/Add wiring.
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Rewire and start testing one subsystem at a time. We can give you suggestions on how to test when you get to this point.
Here is a schematic of my machine when it was nearly stock. This will not be the same as yours but will give you some context of how K40’s were wired.
Scheme-it-export-K40-wiring-2023-11-12-11-22.pdf (628.3 KB)
To provide you with some scope, you would have to sort out as a min. these systems:
The DC power to the M2:
Looks like there is a separate supply on the left sidewall.
Convert the power connector on the current board to a 4-pin that matches the M2
X & Y Axis stepper and endstop connections
The white ribbon cable (CN2) looks compatible as does the CN3 cable.
Verify connections with ohm meter.
Control Panel Connections
Don’t know what the current panel is, post picture
Create a schematic of the power pot, test switch etc.
Connections between the LPS and the M2
L control
AC connections
To control panel
To LPS and DC supplies
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All the thinks Don posted might seem complicated but it’s really just 3 parts/sections which you can mentally group things into.
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your power supply/supplies. There’s usually just the AC power input and then 2 pairs for a 24VDC output and 5VDC output. An external 24VDC power supply will have its own AC input and the 24VDC output is used in place of the original 24VDC output.
NOTE: both power and signals need a path(ie 2 wires which are typically the positive side and the ground/negative side) -
your motion system. This consists of the 2 stepper motors( 4 wires each-2 pairs ) and then 2 limit switches(2 wires each).
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your laser power control system. This on the K40 is often a 3 wire potentiometer(POT) where 5V and ground are put the fixed resistor in the POT and the variable part( the wiper ) is connected to the LPS-IN input for setting the output power level of the laser. The other part of this section is the laser control signal on the LPS labelled L and that is what the controller manipulates under software control.
A 4th section is considered required by some and not so much by others and that is the Laser fire protection system. This is a signal on the LPS which prevents the laser from firing unless switches like a door switch and/or a flow meter switch are closed.
Don knows these systems, in their various configurations, like the back of his hand so if you’re willing, it looks like he is, he’ll walk you through the process to a working machine.
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I still don’t understand why the deal with they with a pot controlling current in this fashion.
I wouldn’t do it this way, I’d let the pwm control the current, not when the tube lases.
Is there no way to limit the lps with these?
Jack, this is how every K40 ships steering this person down a path which is unique is not a great idea. You can do what you want to your K40 but until you prove to all the K40 manufacturers to change how they ship the units or they all start shipping with Ruida controllers how about we not confused people trying to figure this out?
Better yet, start a new thread showing us what you’ve been able to do with a K40 LPS setup the way you’re mentioning? If it gets traction maybe manufacturers will take notice.
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It wasn’t meant to steer anyone anywhere, just question this approach compared to another one that is available and to me a more logical approach…
I have seen them wired differently and with the manual for them showing two ways to connect to the controller.
This is wired up and being used like a solid state laser, with on/off the only option. Tube can be current limited allow full on time at some other current value.
All of you here read schematics and understand these signals, but seem ignore the lase current flow during the on cycle of the pwm period.
At every lase during the pwm cycle, it will do so at the pot setting.
If you’re happy with power/time for your power levels, then I’ll keep my mouth shut.
Guess I shouldn’t question the Chinese or this stuff.