Windows embedded (7) - repurposing a thin client PC

[Voicecoil]

I'm thinking about using a thin client PC for controlling my machine. They're small + low power (so you could mount it inside the control box) & pretty cheap to get hold of. The issue seems to be the operating system, which typically is an embedded version of Windoze set up to run as a thin client - a small computer with little local storage on a network, all settings, apps and data are downloaded from the central server worked on and then returned to it. As such there are a lot of lock downs and pretty well everything is wiped at the end of a session. However Windoze embedded can do a lot more I'm told (I believe it's even been used in one or two In Car Entertainment head units) and would seem ideal for running a CNC machine as it has the power to run normal programs but without all the stuff like Office, Movie Maker and other such floobydust. And it's much smaller than a standard install and I guess might run a bit faster. The issue is how to configure it, the standard thin client setup isn't ideal, has anyone got any ideas please? I know it would be possible to simply delete Windoze and replace with Linux, but I don't have any experience of that and want to get machining ASAP - and I do rather like the look of the UCCNC controllers/software.

[Kitwn]

Had a quick look at the UCCNC website. They sell some little single board computers on there, presumably all compatible stuff with instructions.

Kit

[Voicecoil]

Had a quick look at the UCCNC website. They sell some little single board computers on there, presumably all compatible stuff with instructions.
Kit

I see them, thanks for the suggestion. They look good, but they're not exactly cheap, likely £200 is by the time you've included carriage and an OS. My suggestion of the thin client was because there's loads of them available secondhand for between £20 and £60, if some way could be found to easily convert to a more friendly OS they might be a good solution for lots of us.

[Kitwn]

I know you didn't want to play with Linux but the cheapest option is to do a clean install of LinuxCNC and follow the instructions for updating to the beta version 2.8 (it's been a beta for years and is pretty solid by now) that allows seperate homing of two motors for one axis. You don't need to play with the OS and the setup is straight forward if a bit fidly. See the link below.

I'm not well up on using anything other than parallel ports for this, that may be the downfall for using a modern thin client though legacy machines may have one and you can get PCI cards with them on. Might not be quite so 'thin' once you've fitted it though

I'm no expert but is a low power, possibly low speed Windows machine going to have timing issues? Neither Windows or Linux are real time OSs and pulse timing isn't entirely accurate even on a full power board using LinuxCNC or MACH3. Other people will know more about this issue than I do.


http://www.mycncuk.com/threads/12687...LinuxCNC-v-2-8

Kit

[m_c]

Surely you could just wipe the embedded install, and install a full version of windows?
I'd guess that if it's capable of running windows embedded, it'll run the full version provided you're sensible about what options you install, and use a reasonably specced unit. A basic Win10 install doesn't need that much space, and performs well even low power machines.


Kit, provided you're using an external motion control, timing issues in windows are very unlikely to be a problem. As soon as you use an external motion controller, all motion is buffered, so provided the computer is capable of keeping the buffer topped up, it's not a problem. Those who do experience problems are normally pushing things to the limit, like a computer that meets the absolute bare minimum of specs, or using the same computer to do something processor intensive. There is also the potential issue of windows updates if you leave the computer connected to the outside world (I'd actually suggest win 10 pro, as it gives you much better control over updates if you do plan to have the computer online)

It's also worth mentioning that even in generic LinuxCNC there is a motion buffer, much to the chagrin of the zealots who brandish the whole 'real time' nugget without actually understanding what it means, or how it applies to the whole control process. Every CNC has buffers, it's just that some implementations are not exactly that robust or reactive (Mach3 with an external motion controller is probably one of the worst examples!).

[Doddy]

Much depends on the target platform. For the el-cheapo thin clients, for which their price is a major differentiator, then these /tend/ to be the older, less capable platforms. I've been looking for parallel port support and these often come in with 1-2GB of flash storage, maybe 4GB at a push. MS advertise a 16GB/20GB install for 32/64 flavours of Win10. Going motion controller tends to kick the low-cost solution into the long grass unless you already own such a controller. I've been looking at the thin clients for very much the same reasons as Voicecoil, for a lathe install. Because UCCNC is not particularly lathe-friendly I'm now looking to avoid the whole mess of windows and trial LinuxCNC for the first time, but for that I think I need a machine with a parallel interface. I've got a couple of old desktops - not an ideal form-factor to bolt onto the side of a myford cabinet, but it's starting to look like the best, cheap solution for me.

We need to petition CNCDrive to port UCCNC to Linux :-)

[Kitwn]

m-c,
My understanding is that the best controllers are simply taking their control data and the raw G-code from the PC and generating all the control pulses themselves without having any of the other calls on their processor that go with running an operating system at the same time. This has to be the best way to go in terms of optimum pulse timing but is also the more expensive option. Being able to download a G-code file via ethernet and let it run while the computer is used for other purposes is also an advantage of these more modern designs and is definitely the best way to go both technically and for ease of operation and throughput of work.

My recommendation of LinuxCNC on an old PC is primarily aimed at budget conscious hobbyists like myself. It's cheap, it works, it lets you concentrate the available budget on the mechanical hardware when you first get going. Then you can start making things while you learn just how many worms there are in the CNC can

I use a dedicated PC running only LinuxCNC and did some measurements of step pulse timing a while back. What should have been a continuous stream of pulses at 125uS intervals had most pulses at 125uS but a fairly regular pattern of intervals of 100uS and 150uS as well. There isn't any obvious vibration on the machine, but this is the only CNC machine I have ever used of so haven't any experience of perfectly timed pulses to compare it with.

In the unlikely event of finding myself with nothing else to do I could try building an oscillator to produce a well timed series of pulses and make a comparison but that's not going to happen anytime soon.

Kit

PS Doddy: Saw your reply after finishing the above blather. LinuxCNC is fairly easy to get going if you build a vanilla 4 motor machine and will run perfectly well on an old Windows-XP era motherboard. The LinuxCNC forum is very helpful.

[Doddy]

I can get a new OS on okay, it's trialling UCCNC on W7CE (native install) that's problematic

[Doddy]

Experience so far, dry-fitting a LinuxCNC install. Wheezy (Debian 7 based) has the latency test spiking around 130us, and Stetch (Debian 9) around 180us. Looking at the graphs these are frequent large spikes (circa 1-second, short duration - interrupts? but seemingly random in nature) against a baseline of around 20us. I've looked at SMI and power management - no gains there, and similarly with disconnecting Ethernet and WiFi. Under Wheezy I couldn't get WiFi operation (and it's too archaic to be a comfortable installation). Upgraded 4GB ram to 8GB ram under Stretch with no improvement (though general usage feels better).

Beautiful, small form-factor - the T610Plus is a nice, silent and cool running PC (the fan on a Raspberry Pi 4 drowns out the HP), good connectivity, but not good real-time performance out-of-the-box.

Having scrimped on this, I've now had to spend £300 on a 7176e card to support (though that's as much for the I/O that I want for MPGs and spindle encoders) - I don't think there was much mileage in using the PP for this. Of course, for a linux buff, if you can set core-affinities to OS/interrupts onto one core and LinuxCNC onto the second - your results may vary.

[Clive S]

Experience so far, dry-fitting a LinuxCNC install. Wheezy

I think Stretch is the preferred version for Mesa cards.


http://linuxcnc.org/downloads/