RonGinger
Well-Known Member
The major change in Mach4 is that it uses a motion control device not the PC to do the realtime work. The most common device is the Ethernet connected SmoothStepper. Any function of a parallel port is long gone..
Just to try them out, I used the trial version of Mach 3 and cambam. The lines of g code were limited but to cut simple shapes on a mill it worked great. Eventually I purchased the full version of Mach 3 and it has worked perfectly for me for a few years. When my XP computer died it was easy to find another one for free or for very little cost.Maybe this is my problem? I don't have any special parallel port chord, just the regular one for that computer, I think it's for a printer.
To drive the Sherline controller I will probably have to buy a UC100 parallel port adapter?
I would disagree that the parallel port still plays an "integral role" in the Linux CNC.Hmm ... I haven't seen as pcmcia expansion slot on a laptop here in the US in at least a decade, maybe more. Have laptops sold in other parts of the world have continued to offer that slot?
<rant mode on>
As someone who once made a living working with / designing embedded systems ... I find it endlessly fascinating that the venerable parallel port continues to play such an integral role in both the Mach and LinuxCNC environments. It must be acknowledged that using a parallel port in this way started out as a hack workaround, a way to avoid the expense of a purpose-designed interface card. 30 years later, Ι see what appear to be sophisticated interface / break-out boards with ethernet interfaces ... where the "break out" seems to be little more than the reproduction of a parallel port. Meanwhile - even more of a hack - Windows is being used to drive the signals via real-time bit-flipping, despite the fact that Windows is not a real-time operating system, or at least not without yet more hacking. (Linux is not typically an RTOS either, though its open-source nature allows the design of custom real-time kernels.)
All that to say, I find it hard to understand why USB is viewed with suspicion in this equation, despite the fact that it is regularly used to convey real-time video, even in the lowly USB 2.0 standard. Yes, some buffering and a teeny bit of smarts is needed, but surely that is a much less difficult and expensive approach than continue to funnel everything through a completely outdated protocol which was never designed for the purpose in the first place!
<rand mode off>
Let me be the first to throw stones at my own remarks above: I do not have first-hand experience with either Mach# or LinuxCNC; this rant is based on what I have tried to learn as I have thought about building a system on either platform. It may be that I have completely misunderstood what I have seen as I have researched various options. Please feel free to throw stones as needed!
I assume that is a simple 3 motor open loop stepper system. Do you have the necessary documentation what pin does what on the parallel port?I have a Sherline CNC mill with the Sherline controller box.
Might be the severe lack of shielding available in usb cables.Thanks for correcting my misunderstanding! I am pleased to learn that the real time bit flipping is being done on the controller board. But that still leaves me puzzled as to why USB is not used ... !
As I see it (but that is a good unhealthy dangerous half knowledge) USB is relative unstable and has its flaws focusing more on ease of use for the end consumers. Not so focused on safety.Thanks for correcting my misunderstanding! I am pleased to learn that the real time bit flipping is being done on the controller board. But that still leaves me puzzled as to why USB is not used ... !
If your system is working fine, why change it. My computer was 27 years when I started having issues. I started using the computer as a controller in 2006 and it ran Mach3 flawlessly until just a few months ago. From 2006-2023 I didn't spend a single dime on it so I figured a new computer was well deserved. Now the lathe and mill are updated with a new computer, control panels with motion control boards and Mach4. Now I'm good for another 20 years.
I did real time stuff back in the 70's and early 80's, most of what was critical then just doesn't apply to small machines in the home shop any more. We have crazy fast hardware, lots of RAM, tons of storage space, our processors back then couldn't overflow todays SSDs.Hmm ... I haven't seen as pcmcia expansion slot on a laptop here in the US in at least a decade, maybe more. Have laptops sold in other parts of the world have continued to offer that slot?
<rant mode on>
As someone who once made a living working with / designing embedded systems ... I find it endlessly fascinating that the venerable parallel port continues to play such an integral role in both the Mach and LinuxCNC environments. It must be acknowledged that using a parallel port in this way started out as a hack workaround, a way to avoid the expense of a purpose-designed interface card. 30 years later, Ι see what appear to be sophisticated interface / break-out boards with ethernet interfaces ... where the "break out" seems to be little more than the reproduction of a parallel port. Meanwhile - even more of a hack - Windows is being used to drive the signals via real-time bit-flipping, despite the fact that Windows is not a real-time operating system, or at least not without yet more hacking. (Linux is not typically an RTOS either, though its open-source nature allows the design of custom real-time kernels.)
All that to say, I find it hard to understand why USB is viewed with suspicion in this equation, despite the fact that it is regularly used to convey real-time video, even in the lowly USB 2.0 standard. Yes, some buffering and a teeny bit of smarts is needed, but surely that is a much less difficult and expensive approach than continue to funnel everything through a completely outdated protocol which was never designed for the purpose in the first place!
<rand mode off>
Let me be the first to throw stones at my own remarks above: I do not have first-hand experience with either Mach# or LinuxCNC; this rant is based on what I have tried to learn as I have thought about building a system on either platform. It may be that I have completely misunderstood what I have seen as I have researched various options. Please feel free to throw stones as needed!
I don’t know what an open loop is or what pin does whatI assume that is a simple 3 motor open loop stepper system. Do you have the necessary documentation what pin does what on the parallel port?
See post #25 in this thread for the pin out for the parallel port.I don’t know what an open loop is or what pin does what
I don’t know what an open loop is or what pin does what
For this conversation, open loop refers to a CNC machine being run by software, such as Mach3, which causes one or more axis on the machine to move, but has no way of verifying that the instructed move actually happened. Mach3 simply instructs a stepper motor to rotate some number of steps, it has no way of knowing if those steps caused the X, Y, or Z axis to actually move. More expensive CNC machines have built-in gauges that measure the position of each axis and report that position to the software; this is a closed loop system.
Make sense ?
I would not go for a GRBL base machine myself, because experimenting with sensors, manual pulse generators (MPG) and things like this is part of the fun. I learned the hard way that saving little on the hardware and spending many hours, just to figure out that the cheap solution cannot work, does not "cut it". (or it cut it wrong, which is also not good)....shortened quote...
With the growth of routers and lasers, there are a heck of a lot more gRbl based machines in use every day than Mach4 or LinuxCNC. Many more folks finding and fixing defects, and adding features. Not the right solution for big fast machines like rack and pinion servo based 5X12 routers or to retrofit a Haas (yet), but plenty good for most everything I've ever needed. Maybe I'm just lazy or simple minded, but this stuff is just a way to make parts for my projects, not some religious conversion thing that makes me carry on about some one true way.
SSD can also fail.I have two very old Dell Optiplex 780 desktops running Windows 7 and Mach3, one for my lathe and one for my mill. Several years ago the hard drive on one machine died, which forced me to look for a replacement,... I was pleasantly surprised to find a large selection of SSDs for very reasonable prices. I bought and installed two SSDs, one on each computer. Both computers now boot-up a bit faster, but the real benefit for me is knowing that I'll never have another hard-drive crash when I want to use my CNC machine.
For all those using old computers, like me, consider replacing your old spinning disk drives with a SSD while your old drive is still working.
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