Novamill spindle speed control from Gecko G540

[Ali Kat]

Hi, Just got registered on the Denford forum and I'm looking for some advice or help.

I am converting a Novamill to Mach 3 and I'm using a Gecko G540 driver with 48v 12 amp PSU from CNC4U. So far I have managed to hook up the original steppers and got things moving using an XBox 360 wired controller as well as through the screen / keyboard. I have much to do with setting up Mach 3 (and learning how to use it ) and I may have further queries on things like home switches etc. However, my initial query is to do with spindle control.

After removing all the innards of the "big black box" I have identified the Sprint 400 (?) spindle control board and have spoken to the manufacturer about it's connections. My problem is that the Gecko G540 is only opto isolated up to 110v (for the US market) but the Sprint 400 "floats" at 240v and cannot be connected directly from the G540.

Whilst disembowling the black box I have noted that the signal feed into the Sprint 400 appears to pass from the Smartstep 3 board through an isolator board that feeds out through red and blue wires. The problem is that the input to this board is a multi way ribbon cable. Is anyone able to tell me if I can use this board in my intended set up to control spindle speed and, if so, what connections must I make to the isolator board (i.e G540 0 - 10v output and any other power requirments) and on which connection points?

I should point out that I am NOT an electronic type person - any such references to electronic terms in the above are only what I have noted down in my research. Any replies need to be in a fairly simple format for me to understand.

Ali Kat

[angel-tech]

http://www.diycnc.co.uk/html/spindle_boards.html

the SP3DC is the one you need.

If you need a chat about this i'll pm you my phone number.

[Ali Kat]

Hi Angel tech, I've been following a number of your forum submissions and was hoping that you might pick up on my query.

I've spent a couple of hours looking at the DIY CNC site and in particular the V3 board. I didn't think that the V4 was applicable. just as I thought I had got it sorted in my head I realised that the G540 only outputs 0 - 10v and I would need to strip back the parallel cable to pull out relevant cores for the V3 board. I'm trying to keep it relativley simple and tidy if possible. Would I be correct to think that I could add a second parallel port and run another parallel cable to the electronics enclosure to feed the V3 or V4?

If you could let me know your number it would be good as I will probably have a 101 questions before I'm finished.

Cheers

Ali Kat

[Ali Kat]

This is a follow up to my initial post for the benefit of any one else that may be trying to do a similar thing.

On the advice of Angel Tech, I obtained a V3 board from Roy at DIYCNC and a small 12v PSU from ebay. This set up requires two signals from the parallel port to be fed to the V3 board. Firstly I opened the case of the Gecko G540 to see if I could isolate the signals from pins 1 and 14 - no luck there - it's all pcb and direct connections. The next suggestion was to make up a short DB 25 male to female lead and take the two required wires from this. After a couple of hours of soldering (?) and generally making a hash of things I looked at it from a different angle and decided that it was easier to install a second PCI parallel port card that I had on hand.

This went into the computer easily and Windows XP recognized it as soon as I had installed the drivers. I've cracked it, I thought. Now I soldered just three wires to a DB25 male plug (step, dir and gnd) and connected these to the V3 board, plugged it into the 2nd LPT port and started Mach 3. After telling Mach that there was a 2nd port and assigning the spindle step and direction signals to the relevant pins on this port, I tried to get the spindle moving but, alas, nothing was happening. Testing the V3 showed that there was virtually 0 volts on the analogue output and the relay was remaining open. Lots of fiddling later and I was getting nowhere so I moved the plug to the 1st LPT port (Gecko was not connected during any of this routine) and re-configured the signals and pins. This time the spindle fired up when I clicked on the spindle toggle in Mach 3 - ah, sweet success !

Now, I'm not over familiar with Mach 3 yet so I wasn't too sure on spindle calibration etc. but when I tried this it seemed to spin the spindle at increasing revs - moving up by approx 20% each time. By the way, in order to get this all to work I had connected the "run" contacts on the V3 directly together so stop / start seemed to be controlled only by the step function (?). To prove this, I disconnected the direction signal and it still worked as it had before. I'm not sure if I like this as it doesn't seem to allow any ES on the spindle.

So this is where I am today - spindle is being controlled by Mach 3, after a style, and is going in the correct direction and it would seem that I can probably adjust the RPM through Mach when I find out how. But it won't work on LPT 2 and the relay on the V3 doesn't pull in as I had expected on the V3. I am thinking along the lines of checking the outputs from LPT 2 to see if Mach is actually sending any signals to the port. I'm not sure how to do this as I am not an electronics type person (give me a welding machine any day), but I beleive it is possible with an LED and a 470 ohm resistor (?).

Any feedback or suggestions would, as always, be gratefully accepted.

Cheers

Nick

[angel-tech]

morning Nick. It sounds like you don't have the 2nd port set in mach. Pop into control panel on the pc and go to system/device manager, in there you can look at ports (com & lpt). Lpt3 resources will show an i/o range, put the first value in mach (eg. 0378) then check if you can switch the relay on the board.
Have you checked that the software is fully loaded for the second p/port, and you have the correct settings in mach outputs (port 2).

Feel free to give me a ring if you need a run through.

[Ali Kat]

Hi AT,

I'm not at home until Thursday so I can't check the computer 2nd port but I did wonder if I had completed it correctly.

I've just checked on a copy of Mach 3 that I have on my laptop and I note that in the config ports and pins menu Mach has already assigned a port address for 2nd LPT, irrespective of the enable box being ticked or not. I'm beginning to wonder if I've assumed that this address was correct when, in fact, this is just a default address and the actual address that the computer has assigned to the board is different. I won't be able to test this theory until Thursday night but I'm hoping that the answer could be that simple.

However, even if this solves the 2nd LPT issue, I still can't understand why the spindle operates on the step signal only and the dir signal is not doing anything.

Cheers

Nick

[angel-tech]

have you set the outputs correctly in mach

[Ali Kat]

Once again I thought that this was a basic error and things would be spinning soon - wrong!

I had convinced myself that I had not set the 2nd port correctly so as soon as I got home I checked in windows device manager and, sure enough, it had allocated a different i/o range than Mach 3 had assumed. Easy I thought, just change it and things will work but it's not as simple. The i/o ranges assigned by Windows XP to the 2nd LPT port (LPT3) are:
E200 - E207 and E300 - E307

whereas the i/o ranges for LPT 1 are:
0378 -037F and 0778 - 077B

Mach 3 correctly assigns LPT1 (although it appears as 0x378 in the "config ports and pins" box). However, I cannot get Mach to accept Ex200 (which I assume is the way it wants to read it) although it accepts 0x200. Even though it accepts 0x200 the port still does not operate the spindle as LPT1 does.

One other thing:- LPT3 is reported as a PCI ECP port wheras LPT 1 is reported as an EPP +ECP port. I cannot seem to find a way in the Shuttles bios to make LPT3 an EPP + ECP type port.

I am now beginning to realy struggle so any help would be good.


Cheers

Nick

[angel-tech]

Just type in E200. and don't worry about the ecp on port two.

[Denford Admin]

(I don't know anything about Mach sorry)
Just wondering why the 2nd port has come up as LPT3 ?
Is there an optional 2nd LPT on the motherboard you can disable in BIOS ? I'd imagine things would work better if the 2nd port actually was LPT2.
According to Wikipedia, LPT3 shares LPT1's interrupt.

Is there a driver configuration utility for the PCI parallel port ? I'd imagine you'd be able to change the ECP and port values from there (rather than the PC's BIOS)

[Ali Kat]

After a lot of help from Angel Tech I've now got Mach 3 operating the Novamill's 3 axis and the spindle stop/start and speed. Eventually I had to break out three wires from the parallel cable to feed to the V3 board that, in turn, feeds the spindle control board.

Whilst it's all working nicely, I'm still not happy with the amateurish look of the cable that I've broken out from and I would really like to have used the second LPT port. This has also renewed my urge to find out why the 2nd LPT port is not working as it should. To add to the confusion, when I plug the Gecko cable directly to the 2nd port and re-assign the port number in Mach it seems to work correctly, albeit the charge pump has to be switched off on the Gecko. The remark from Denford Admin regarding the numbering of the port and possible shared interupts makes me curious and I will be looking at these as soon as I get back home at the end of the week.

If anyone is reading this and has any input it would be gratefully accepted. To help in this direction I should give some details of the set up:- The controlling computer is an oldish Shuttle XPC (SB51G I think) to which I have had to install a PC8 parallel port adapter directly to the motherboard as Shuttles are not often fitted with them as standard. This is LPT1 and seems to work fine. With the tales of woe above, I installed a PCI parallel port card along with the drivers that were supplied with it. I am unable to find any reference to the 2nd LPT port in the Shuttle's BIOS so can't make any changes there but it is recognized in Windows XP Device Manager as LPT 3. However, there doesn't seem any way to change the LPT number or configure the port as EPP / ECP etc.

I am determined to get to the bottom of the issue and will keep trying variations until I get it all running as I want. Meanwhile, my thanks, once again, to Angel tech for "showing me the light".

Cheers

nick