CNC Parallel Port - Unknown Pins! (Mach3)

Hello, I'm very new to the CNC world, I recently acquired a large CNC router which is quite old. I know it all works because I have some software which came with it and I'm able to drive the motors and even run Gcode.

The problem is, I'd like to use Mach3 (primarily because I want to use a newer PC), but I have no idea what the pin settings are suppose to be!! The software which came with the CNC is **very** basic and doesn't have any settings or configuration files which might suggest which pins do what on the parallel cable. Worse yet, I believe the controller board has been replaced from the original, so even if I had the manual it wouldn't help.

I have tried using a port monitor but the results I'm getting don't make sense to me, for instance, when I move in the X+ axis, I'm expecting to see one of the pins light up with activity, but that doesn't happen...But I'm still learning so maybe I've got it wrong??

I'm hoping someone might know of a way I can determine what my settings in Mach3, or any other program for that matter, should be? Is there a series of tests I can do to figure it out?

Thank you!

Are you sure it's a parallel cable? Could it be a proprietary comm cable or a serial cable?

Any idea what controller is in it? What is the model of the router?

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Originally Posted by Butterhat

I have tried using a port monitor but the results I'm getting don't make sense to me, for instance, when I move in the X+ axis, I'm expecting to see one of the pins light up with activity, but that doesn't happen...

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"Port monitor" meaning a program or a hardware device?

If it's a program, it may not work at all. CNC control software normally assumes full control of the LPT port, I don't think you can monitor port activity with any third party software.

If it's a hardware device, make sure it's made for the LPT port and not 25-pin RS232 port.

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Originally Posted by Jim Dawson

Are you sure it's a parallel cable? Could it be a proprietary comm cable or a serial cable?

Any idea what controller is in it? What is the model of the router?

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Yes, it is a parallel cable. Unfortunately, I'm not sure what the controller is, I took a look at the controller board but it didn't appear to have any model # on it. The Router is a Multi-Cam 48

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Originally Posted by CitizenOfDreams

"Port monitor" meaning a program or a hardware device?

If it's a program, it may not work at all. CNC control software normally assumes full control of the LPT port, I don't think you can monitor port activity with any third party software.

If it's a hardware device, make sure it's made for the LPT port and not 25-pin RS232 port.

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I used software to try to monitor, so that was probably my issue there. Can you recommend some hardware that would allow me to monitor the signals?

Thank you

pictures tell a 1k words...

A regular voltmeter would be enough to identify a pin that has some activity. Either that, or any small LED and a series resistor (500 to 1000 ohms should work).

Another way is to study the controller board and see which signal goes where.

Yet another way is trial and error. There are only 12 output signals, it does not take much time to match one of them and go from there.

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Originally Posted by machinehop5

pictures tell a 1k words...

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Butterhat is a new CNCzone user, he does not have permissions to post pictures yet.

I would not expect a Multi CAM to have a parallel port controller.

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Originally Posted by ger21

I would not expect a Multi CAM to have a parallel port controller.

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A 25-pin COM port then? Or a proprietary I/O card? What did those machines use?

911 the time was 911 and 15 seconds....beep

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Originally Posted by CitizenOfDreams

A 25-pin COM port then? Or a proprietary I/O card? What did those machines use?

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I think the older ones were serial, the newer ones are Ethernet. I think the pendant was a direct wire to the controller board.

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Originally Posted by Butterhat

I'm hoping someone might know of a way I can determine what my settings in Mach3, or any other program for that matter, should be? Is there a series of tests I can do to figure it out?

Thank you!

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If your Multicam really does use a 25 pin parallel port connection between PC and control cabinet, it may have already been modified. If the original motion controller board is still in the machine, you can not connect THROUGH it anyway. You would need to bypass it.

The last Multicam I worked on had an Extratech Control with the Pendant. Files were sent via 9 pin serial cable, and the jobs were picked up and run with the Pendant. As I recall, the machine at that time did have individual motor driver cards and would have been easy to hack a different control into it. You will need to send photos of the inside of your cabinet, and perhaps some here can identify what you have inside and where you can go from there. A lot of those OEM's did use off the shelf drives (for some reason IMS rings a bell), and that would be easy to interface.

Thank you for all the responses!

I'll see what I can do about getting some pictures, maybe posting them elsewhere with a link if I'm unable to post on the forums.

The CNC definitely does connect with a 25 pin Parallel cable that plugs into the computers LPT port (currently on address 0x378)

And as mentioned before, the controller board is not original, I believe the previous owner had replaced it to work with parallel.

I hope I'm not breaking any forum rules here, but, as promised, here are some high-res photos of the controller box.

https://ibb.co/6rXkC2V
https://ibb.co/m5y9L9s
https://ibb.co/t8TqqDn
https://ibb.co/v34D3Gx
https://ibb.co/JdtcKsM

There's some green tape with X, Y, Z information on it, not sure if that's anything of importance? Again, I'm *VERY* new to this stuff!!

The circuit board says "Larken" on it, which I believe is a local CNC shop, I will try contacting them but they were unfortunately pretty unhelpful when we tried contacting them last year.

That is some kind of proprietary controller board. Looks like the drives are standard step & direction input. You need to replace the controller board with modern hardware of your choice. Then you can run Mach3 if you want.

Wiring a parallel port breakout board from scratch is, IMO, easier to do than what you are trying to do. Just rip out the wiring, or manually trace it back to the drives.

All you have is step and direction wires to 3 drives, and a handful of other wires to switches.

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Originally Posted by Butterhat

I hope I'm not breaking any forum rules here, but, as promised, here are some high-res photos of the controller box.

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Well, that let me know my memory is still sharp... IMS drives.....

You have a fairly simple environment to convert to a new control. Those three wires coming from each motor drive are typical to all sorts of hobby level controls. One is STEP, one is DIRECTION and the third is a COMMON. The drive PC boards may be marked as to which is which, but you may as well download the documentation for the drives so you can eventually adjust your preferred resolution. One would assume the output amperage settings are already correct, and no changes need to be made on the high voltage side of those drives.

Personally, I'd spend the money for Flashcut CNC as they have a very nice fully capable Cad (drawing) / Cam(G-code creation) system built right into the control software. While I've seen some pretty lame, partially effective attempts at built in Cad/Cam, these guys really knocked it out of the park.

An added plus is they can advise you with exactly how you need to interface what you have there.

If your on a much tighter budget, there are many, many controls you can connect to those drives and end up with a formidable machine, but you will need to do all the learning and legwork yourself to get under way. If you have a good understanding of wiring, electrical theory and commitment, your set.

I'd avoid the old Mach3 like the plague unless your really looking to learn/experience unexplainable quirks no one should really have to understand or accept.