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John Stevenson
04-22-2010, 04:51 PM
I often need to buy computers with parallel ports for CNC machines to run on.

These are for retrofits as opposed to new machines as we do a fair few Denford and Conect conversions and we supply a new machine with the job, just a base unit.

In the past we have been buying new budget commercial machines, many with Linux pre loaded, then buying a copy of XP.

Just lately the supply of parallel port machines has been drying up and we have been looking at older surplus machines. Made a few phone calls the other day and today took delivery of some Dell GX260's for 30 each, about $45
80 GB hard drives all wiped and the copy of XP reinstalled and the hologram is on the case.
To make the deal better they come with a HP 15" TFT monitor, keyboard, mouse and all the cables.

To make the deal even better if any stop working in 3 months they will swap them.

I can't buy a windows licence for this price.

psomero
04-22-2010, 05:07 PM
that is a good price.

are you aware of parallel port to usb converters? they usually work a ton better than on-board parallel ports in XP as the drivers are more modern.

i own about a dozen serial to usb converters. i don't even bother with the on-board ports on any of my machines any more, as you need to go into the bios settings to change any of their parameters...

clutch
04-22-2010, 05:08 PM
Windows? There is something called EMC2 you know. :rolleyes:

Clutch

CountZero
04-22-2010, 05:25 PM
USB-PP converters are useless for CNC, they are only useful for printers. At least the ones I have seen.

You can buy PCI cards with a "real" parallel port

aboard_epsilon
04-22-2010, 05:30 PM
the s/h hologram stickers sell on ebay

xp home 10 - 15
xp pro 15 - 25

or from a car boot sale stuck on the side of a maybe working computer for 5.

all the best.markj

Black_Moons
04-22-2010, 05:31 PM
Wow, I could buy a fully functional PC for less then eating at a fancy restrant.

Countzero is right, anything over USB will be limited by the USB timing specs, And well, basicly its like this: There is no guarentee to timing, Not even close. things that 'hack' lpt to bitbang stuff will never work.

Stuff that uses proper LPT protocols may work, but still not guarenteed, and basicly if your LPT port is outputing dir/step signals to stepper/servo controllers, its not gonna work.

PCI/PCI-express/etc LPT cards do exist, and should work fine.

Another thing to look at, is actual USB based CNC sollutions
While USB timing is unreliable yes, that does not stop a CNC from having a smart microntroller to buffer instructions and provide all the pulse/step information from those instructions.

I don't know of any such USB CNC sollutions, but im sure some exist.

I do seem to recall now of some PCI card based CNC sollutions.

EVguru
04-22-2010, 05:46 PM
I do all the official wiping of machines at work that are replaced on a rolling program.

They get sold to staff first, then donated to charity with the non functioning dregs going for recycling. A Dell GX280 base unit, with 80 GB disk and 2GB ram sells for 45 (free mouse and keyboard), so 30 with monitor is a steal.

I get to pick over the scraps, so can usually build functioning machines for myself.

My mill has servos and the parallel port would struggle with the pulse rate, so I'm going down the Smoothstepper route.

John Stevenson
04-22-2010, 05:53 PM
No the USB converters wont work with Mach, I know we can buy PCI cards but at this price as I said I can't buy the license for XP

We have looked at EMC2, in fact we have a lathe running on it.
The problem with EMC and this is not a Windows v Linux argument is that we have to support first time CNC users who have a massive learning curve ahead of them.

Most are conversant with windows and throwing a whole new operation system into the box is going to faze them probably enough that they don't make the leap in the first place.

Secondly although they don't realise it it EMC is written by geeks, for geeks and I mean this nicely as I know a few of the developers.

If you ask a question you get an answer but it's in geek speak and they can't get over that others are not as advanced as they are.

Thirdly it's a toy to the developers not a tool, if they don't see that a function is needed by them it doesn't get implemented.
There are not just the release on the web but many tweaked copies done by folk who want different things but they never get back so there is never a master copy.

If you break a tool in EMC you can't jog off, change the tool, reset the Z offset and run from here, that isn't in the code.

Les Newell in the UK altered that last year, sent it up but it's still not been written in. Because the developers are programmers and not machinists that isn't a priority for them.

John Stevenson
04-22-2010, 05:56 PM
My mill has servos and the parallel port would struggle with the pulse rate, so I'm going down the Smoothstepper route.

Paul,
I have just sold all mine and the C25 breakout boards but I know of another Smooth Stepper that's for sale in the UK, cheaper than buying from the US and the customs hassle

Evan
04-22-2010, 06:48 PM
DX does have a real USB parallel port solution but unfortunately it is back ordered right now. It won't beat the price John is getting but if you need a real standard parallel port DX has a port replicator that provides serial via a real UART, SPP via a real parallel port chip and two PS2 ports plus two USB pass through ports. It only needs USB 1.1 and it is compatible with 98, 2000, XP and Vista and costs $22.

http://www.dealextreme.com/details.dx/sku.22685

EVguru
04-23-2010, 02:57 AM
I know of another Smooth Stepper that's for sale in the UK, cheaper than buying from the US and the customs hassle

Put my name on it please!

I'm off to the Stafford bike show for the weekend (My Morini 3 1/2 Sport will be on the club stand), but I should be able to drop in to the Forum in the evenings.

John Stevenson
04-23-2010, 03:12 AM
DX does have a real USB parallel port solution but unfortunately it is back ordered right now. It won't beat the price John is getting but if you need a real standard parallel port DX has a port replicator that provides serial via a real UART, SPP via a real parallel port chip and two PS2 ports plus two USB pass through ports. It only needs USB 1.1 and it is compatible with 98, 2000, XP and Vista and costs $22.

http://www.dealextreme.com/details.dx/sku.22685

Evan, That looks interesting but the info wasn't really forthcoming as to whether it would work or not.
Mach is quite unique in that it takes over the PC first and tells windows what to do second so it may or may not work but to prevent any argument I rang Art Fenerty up and asked him if it would work and secondly if it would does it need a plug in writing for it.

Unfortunately the answer on the first count was no it wouldn't work, pity as that's another avenue closed.

.

John Stevenson
04-23-2010, 03:13 AM
Put my name on it please!

I'm off to the Stafford bike show for the weekend (My Morini 3 1/2 Sport will be on the club stand), but I should be able to drop in to the Forum in the evenings.

I'll PM you the guys details when I have spoken to him today and you can deal direct

macona
04-23-2010, 04:13 AM
Evan, That looks interesting but the info wasn't really forthcoming as to whether it would work or not.
Mach is quite unique in that it takes over the PC first and tells windows what to do second so it may or may not work but to prevent any argument I rang Art Fenerty up and asked him if it would work and secondly if it would does it need a plug in writing for it.

Unfortunately the answer on the first count was no it wouldn't work, pity as that's another avenue closed.

.

It will not work for CNC. There is always the smoothstepper but it has not seen any work on it in a long time. There is not a whole lot out there.

Oh yeah, there is the KFLOP board.

oldtiffie
04-23-2010, 05:50 AM
I have two pretty new and pretty good computers - one running XP Pro and the other W7 Pro - and both main boards have serial ports plus I have a new main board (matched) for each computer. The computer that I have ordered for my CNC-ing (Mach3) of my Sieg X3 mill (and perhaps a lathe later) has XP on it as well as a new and a spare main board both of which have serial ports.

I bought them with Mach3's requirement for a serial port in mind.

Main boards with serial ports are very hard to get - same with IDE HDD drives (now SATA2). My machines have one IDE channel - for a CD/DVD "burner" and a single IDE drive. They are all SATA otherwise.

tumutbound
04-23-2010, 06:08 AM
oldtiffie,
I hope you meant parallel ports not serial ports.
Mach3 requires at least 1 parallel port.

oldtiffie
04-23-2010, 06:45 AM
Sorry Geoff.

I guess I am in a parallel universe - the fourth dimension? That will drive the 3-D CAD gurus nuts!!.
http://en.wikipedia.org/wiki/Fourth_dimension

or through the looking glass? - give 'em something to reflect upon?:
http://en.wikipedia.org/wiki/Through_the_Looking-Glass

Parallel is what I meant (to say).

No excuses - I cocked it up.

SNAFU? damned right!!

Evan
04-23-2010, 06:49 AM
There is one motherboard still available that has a real parallel port included along with just about ever other port type as well. It was recently discontinued but there is still stock at some online retailers. It's the ASUS M2N68-VM. The parallel port isn't brought out to the back but all it needs is a simple cable with D-sub connector.

I have the board and it works well with a dual core Athlon at 3 gigs over clocked.

Here is one source:

http://www.alvio.com/xABK_PID498360_asus-computer_m2n68-vm_asus-m2n68-vm-am2-am2-nvidia-geforce-7050pv-hdmi-micro-atx-retail_amd-socket-am2-motherboards.html

kf2qd
04-23-2010, 12:32 PM
You might also want to look into windows 2000. Runs Mach3 and uses less overhead than does XP. On a faster machine it really flies. I have a 700MHz machine that handles Mach3 just fine, a 1.8 or 2.0GHz machine would be awesome.

kf2qd
04-23-2010, 12:38 PM
You might also want to look into windows 2000. Runs Mach3 and uses less overhead than does XP. On a faster machine it really flies. I have a 700MHz machine that handles Mach3 just fine, a 1.8 or 2.0GHz machine would be awesome.

psomero
04-23-2010, 12:45 PM
ah, that's a good point about the usb converters and their potential timing issues.

i've used them for interfacing with microcontrollers, but nothing that was truly time-critical like controlling a machine yet.

they do work great for stuff like low cost DAQ over rs232, which is what i've done primarily...

Farbmeister
04-25-2010, 03:47 AM
Timing? As in interrupts or date rate?

Parallel ports MAX out a 2MB/s USB 2.0 60MB/s

Anyone have a spec on the speed of the actual UART at the end of the cable converting USB to Parallel? Stepper drivers don't send anything back, servo's do.

Seems like a small mod to make drivers USB capable.

http://en.wikipedia.org/wiki/List_of_device_bandwidths

Evan
04-25-2010, 05:49 AM
Wikipedia is wrong but that is no surprise. 480Mbits per second divided by 10 is 48MB per second. Yes, 10, not 8 as there are framing bits to consider. Then, the maximum bit rate cannot be attained to any single device.

That really isn't the issue. It is consistent timing that matters. The USB protocol allows for a timing delay between nearly zero to the time it takes to echo over 90 feet of twisted pair. USB is an asynchronous protocol meaning that consistent timing is not assured.

Mach III uses a ring zero driver to bit bang directly to the registers of the parallel port interface (not a UART). Any USB solution would have to virtualize the Mach III driver and interpose a HAL between the USB device and the MACH driver to intercept and translate the direct access reads and writes of the I/O registers. This isn't impossible but it is far from simple

BobWarfield
04-25-2010, 11:31 AM
This parallel port problem is such a silly business. Mach3 is a great piece of software, but its a train running full speed towards a bridge that is out.

The actual hardware needed for something like a Smoothstepper is trivial. But these parallel port alternatives keep getting killed for lack of software over and over again.

I was saying over on the Mach3 board that they need to release a single fixed API for all these boards instead of writing custom plug-ins for each and every one of them. That way, at least the software might only have to be written once and we could actually get through it before whomever loses interest.

Cheers,

BW

Evan
04-25-2010, 12:20 PM
It isn't quite that bad yet. I just searched Tiger Direct and there are 13 Intel and Asus motherboards still made that have a parallel port. I didn't bother with all the others but the parallel port ain't dead yet.

macona
04-25-2010, 02:11 PM
I cant imagine not being able to find a parallel port PCI card for a machine if it didnt come with one. It dosnt look like they are going anywhere soon. You can even pick up parallel port cards in pci-e form.

The problem with the USB machine controllers is not lack of software. They talk to Mach 3 just fine. Problem is support and things like threading on the lathe and backlash comp.

A USB cnc controller has the motion control engine on the board itself. They take packets of data from mach and process them on board. Thats the only way it can handle timing and reliably control things like estop and limits.

The Gecko G100 was a complete failure and the smoothstepper, well, I dont know whats up with that thing. Dont know if they ever fully supported threading and I know they never supported backlash comp which is a killer for me. None of them have ever supported closed loop spindle.