[Zig]

OK .. we are all happy to have the new PC which runs like the clappers.

Grat to have the USB and firewire ..and .. not so great to loose paralel port.

Looking for a new PC to replace the existing machine runing EMC software.

Paralel port is a must as is decent latency performance.

Looking for advice and experiences with the modern ( still available ) motherboards suitable to run EMC.

Any experiences welcome in particular anybody using the Jetway J7F2WE1G or J7F2WE2G boards.

[Zig]

Well seems no takers.

Ok new motherboard has parallel port.
An MSI board model K9 SLI V2 running with a dual core AMD Athlon X2 processor at 3.1GHz.

On the face of it meets at least one requirement... runs like the clappers.
mobo loaded with ATI X300 PCIX16 video card and 2 Gbyte of 667MHz DDR2 memory.

Latency timing unimpressive. In facrt poorer latency timing than the old MSI KM2M Combo L ( about seven years old )

K9 latency performance greater than 14500ns

Hope to have some figures on the jetway offering soon.

[acondit]

OK .. we are all happy to have the new PC which runs like the clappers.

Grat to have the USB and firewire ..and .. not so great to loose paralel port.

Looking for a new PC to replace the existing machine runing EMC software.

Paralel port is a must as is decent latency performance.

Looking for advice and experiences with the modern ( still available ) motherboards suitable to run EMC.

Any experiences welcome in particular anybody using the Jetway J7F2WE1G or J7F2WE2G boards.

Did you look at the info in the wiki here?
I also found this in the archives of the EMC user list.

From: Len Shelton <len@...>
Subject: Re: Via motherboard
Newsgroups: gmane.linux.distributions.emc.user
Date: 2007-02-15 04:04:07 GMT (1 year, 44 weeks, 1 day, 7 hours and 11 minutes ago)

FWIW - I just upgraded my Mini-ITX setup to a

Jetway Mini-ITX Motherboard,VIA C7 1.5GHz,J7F2WE1G5D

>From these guys: http://search.ebay.com/_W0QQsassZfremontgangsQQhtZ-1 for
$129.00

http://www.jetwaycomputer.com/itx.html

A little more than pricey what you are looking at, but this little board
rocks!

Ubuntu installed without a hitch, and this is a fast little board. It's a
world of difference from my old C3 processor board. Be prepared to buy DDR2
memory, though.

I don't use Xylotex, but this has a parallel port on an IDC26 connector that
would bridge nicely to one of them.

>Len

Alan

[Zig]

Hello Alan,

Thanks for the response.

Amajor problem is getting hold of some of these products.

I have corresponded with Jetway but have had no joy in finding a suitable source In Australia.

There are two companies listed as being able to supply but neither has stocks.

One of them didnot seem to know waht they were promoting, asked me send em an email describing the hardware I was after.

Anyway the great thing about Jetway offering is that itis also available in a 2 Gig version and that it also has a powersupply which will run off 24V ( mobile application).

Presently all of my servo run off two 12 V car batteries. I am hoping to get the entire system to run of 24V and be to a certain extent isolated from mains supply; effectively keep batteries on chareg constantly and ensure no machine glitches in case of power loss.
Spindle is varible frequency induction motor driven maximum voltage 33VRms at 100 K RPM. Will talk to driver manufacturers to see what can be done to proof it against supply variations

Current computer will allow me to reach maximum speed of approx 230 mm / second ( approx 540 inches per minute ) with a resolution of 5 micron

[jmelson]

OK .. we are all happy to have the new PC which runs like the clappers.

Grat to have the USB and firewire ..and .. not so great to loose paralel port.

Looking for a new PC to replace the existing machine runing EMC software.

Paralel port is a must as is decent latency performance.

Looking for advice and experiences with the modern ( still available ) motherboards suitable to run EMC.

Any experiences welcome in particular anybody using the Jetway J7F2WE1G or J7F2WE2G boards.

My solution, both for myself and for customers who want me to put EMC2 on a computer for them is to buy off-lease Dell computers on eBay. I use the Optiplex line of commercial-grade desktop machines. These all work well with Ubuntu and EMC2, and have also proven to be VERY reliable. I have been using various machines from 600 MHz to about 1 GHz. All are adequate for use in servo systems with controller boards, the higher-end CPUs would be best for use when generating step pulses in software. These Dell machines, even very recent ones, still have parallel ports.

Jon

[baden0001]

My solution, both for myself and for customers who want me to put EMC2 on a computer for them is to buy off-lease Dell computers on eBay. I use the Optiplex line of commercial-grade desktop machines. These all work well with Ubuntu and EMC2, and have also proven to be VERY reliable. I have been using various machines from 600 MHz to about 1 GHz. All are adequate for use in servo systems with controller boards, the higher-end CPUs would be best for use when generating step pulses in software. These Dell machines, even very recent ones, still have parallel ports.

Jon

Have you had to fix the SMI issue as shown on

http://wiki.linuxcnc.org/cgi-bin/emc...ixingSMIIssues

If so, have you had any overheating problems?

Thanks,
Will Baden

[jmelson]

Have you had to fix the SMI issue as shown on

http://wiki.linuxcnc.org/cgi-bin/emc...ixingSMIIssues

If so, have you had any overheating problems?

Thanks,
Will Baden

These are Pentium 3 desktop machines, and I don't think they use the SMI interrupt. I think the fan speed controllers are pure hardware (many even have the speed controller built into the fan motor itself) and the CPUs run full speed all the time.

I think this whole idea of putting extremely marginal cooling on laptop CPUs and then throttling the CPU speed to prevent overheating is really shoddy design. It would be like not putting a radiator on a car and then shutting down the engine whenever the inevitable overheating occurs!

Jon

[samco]

Here is a list of computers/motherboards that have been tested and their results..

http://wiki.linuxcnc.org/cgi-bin/emc...l?Latency-Test

sam

[baden0001]

Here is a list of computers/motherboards that have been tested and their results..

http://wiki.linuxcnc.org/cgi-bin/emc...l?Latency-Test

sam

Thanks for the info Sam, I have been glancing through them every now and then. I am interested in using a Dell since they are cheap and complete.

From what I can tell I would have to build a machine from that webpage, and since I am not very well versed on building a PC I am kinda shy to put one together.

Thanks,
Will Baden

[Zig]

A few hundred dollars down the road and some new data to hand.

The old MSI Athlon ( 1.9 Ghz i think ) motherboard KM2M Combo ( MS-6738 ) with latest bios is offering latency figures in the 18000 nS area.

Good for high speed traverse of about 240 mm/sec

The later MSI K9N SLI V2 motherboard with a dual core X2 processor at 4.8 GHz ( i think ) is good for a latency figure of 22 000 and correspondiglu lower high speed traverse of 205 mm/ sec which is a disapointing figure given a much higher performance of a dual core cpu. Granted its graphical performance is better than the older PC.

Hope these numbers are of help.

[BMG]

Sexy motherboards and graphics are not necessarily the cats meow for EMC. If you look at that list, one of the best latency results came from a compact Deskpro EN. Not necessarily curring edge technology.

If you are planning on setting the computer to just run EMC, then why not get an older model as Jon suggested for little money. For me, I got a bunch of computers from work for free - they were just building up and inventory to make a trip to the recycler so I saved them a trip.

EMC just works provided the latency is low and the MOBO is a reasonably fast machine (PIII and 600MHz is current minimum standard). For servos, it is my understanding that the latency times are less critical as compared to steppers (Corrections from others if I am mis speaking here).

General consensus reading the EMC mailing list lately is that new motherboards are sacrificing realtime for graphics and "game performance".

For EMC Realtime latency minimums for the MOBO dominate

MOBO speed comes second

[digits]

IMHO this is one of the biggest PITA's with EMC2 - finding a motherboard that will play nice! Most cheap and cheerful motherboards have integrated GFX these days, and even if you can turn it of and use a VESA driver, you do actually want decent OpenGL performance to run the Axis GUI.

I also don't want a PC the size of a filing cabinet to drive my machines, so I tried using an old Mini-ITX board I had lying around. With 6.06 it worked fine, but with 8.04 it wouldn't produce sensible latency results, even with the VESA driver! I've ended up with a very painful install of the latest 8.04 kernel on a reinstalled 6.06 system, just so I can have the same RT compile platform as my other machines, but a working GFX driver.

For me, hoping to find useable motherboards from the second hand market isn't an option - I want to be sure I can hot swap a dead motherboard for something new that I can get on next day delivery.

What I would like to know is can motherboards with bad latency results in the high-speed thread work OK if the step generation is being done in hardware instead of S/W?

Alternatively, can EMC2 be run on a machine without X at all? I have mine setup to run emcrsh with a gui on a remote machine, but EMC doesn't seem to want to run on the main machine unless X is running.

Cheers.

[jmelson]

I
For me, hoping to find useable motherboards from the second hand market isn't an option - I want to be sure I can hot swap a dead motherboard for something new that I can get on next day delivery.

Well, I use these Dell Optiplex commercial-grade boxes that I get off eBay for $50 - 75 delivered.
I am having some troubles with the latency, too, but haven't fully dug into it yet.

What I would like to know is can motherboards with bad latency results in the high-speed thread work OK if the step generation is being done in hardware instead of S/W?

Up to a point, yes! The problem is if the latency is unbounded, then it won't work. If the latency is held to a modest bound, then it will have minimal effect on the servo. So, if you have a 1 KHz servo cycle, and the latency never exceeds 100 us, then you only have a 10% jitter in servo sampling time, that's not too bad. As long as the latency never exceeds 1 ms minus the servo compute time, the system will still run OK, but there will be a slight glitch when the servo position is sampled almost a whole period late. That looks to the software like a sudden doubling of velocity for one sample.

The Dell I'm working with right now had latency spikes to 3 ms, so that has to be solved before it can be used. (Since it will be a bench test machine, it doesn't HAVE to be solved, but I want to know how to fix this.)

Alternatively, can EMC2 be run on a machine without X at all? I have mine setup to run emcrsh with a gui on a remote machine, but EMC doesn't seem to want to run on the main machine unless X is running.

Cheers.

Yes, but you have to know that X is not the entire problem. With some driver/video board combinations, it can be part of it. I suspect bit block transfers are being done in kernel code with some of these drivers. But, there are a bunch of other things, especially power and thermal management that can also grab the CPU beyond control of the real time scheduler.

Jon

[jmelson]

Have you had to fix the SMI issue as shown on

http://wiki.linuxcnc.org/cgi-bin/emc...ixingSMIIssues

If so, have you had any overheating problems?

Thanks,
Will Baden

I tried to install this fix, and the first thing is to :
apt-get source rtai-3.3

but, I get the following error:
E: Unable to find a source package for rtai-3.3

Anybody know what to do?

Thanks,

Jon

[acondit]

Jon,

Go to the rtai website, click on "RTAI repository", scroll down the list to "rtai-3.3.tar.bz2".

Alan

[jmelson]

Jon,

Go to the rtai website, click on "RTAI repository", scroll down the list to "rtai-3.3.tar.bz2".

Alan

OK, thanks! While working on this, I was logged in remotely to the machine in question with ssh, and decided to run the latency test. I was getting a nice 14.9 us jitter on the base thread, and 8 us on the servo thread. Note, nothing going on with the video card here. So, I think that means that the actual problem is the video driver, not the smi. So, I didn't implement these changes, as I wasn't sure what other ramifications it could have. I ran glxgears, and was surprised to find it even worked across the net, but when I saw the numbers, I knew it was all running on my local machine, which has a good Nvidia card. (1800 FPS) Anyway, one other bizarre quirk I discovered is I tried to run Firefox on the remote machine, just displaying on the Xserver locally. But, when I downloaded the rtai file, it appeared on the local machine. So, somehow when I type "firefox" in the ssh shell on the remote machine, it diverts it to run it on the local machine.
(All this is to avoid moving the video, kbd and mouse plugs back and forth endlessly.)

So, I am going to try a few different video cards in the machine and see what works best. I don't need real good OpenGL performance to display typical Axis screens on this machine, so absolutely awful performance should be fine.

Thanks,

Jon

[jmelson]

[Continuing along this line, I put an Nvidia Riva TNT board in the computer, and ran it for a while. I was getting jitter of 10561/11695, which sounds quite good. Much better than the Intel 810 video.

Anyway, I'm stuck at 800x600 resolution. I have downloaded the Nvidia legacy driver for this card, but it required you to have net access and NOT be running X to install it. I usually just type "init 3", but apparently the Ubuntu 8.04 default runlevel IS 3, instead of the more usual 5. I can go to runlevel 1, but then the net, etc. is down. Going even to runlevel 2 brings up X. So, is there a way to set the OS so it is fully up, but not running X?

One curious thing, this motherboard had a little card plugged into the AGP slot with 2 Nanya memory chips, the card says "smart" and "aimm-133" on it. I'm guessing this is a video memory that maybe relieves the graphics load on general system memory. I removed this to put in the Nvidia card.

Thanks,

Jon

[samco]

I think people have had luck with the 'vesa' and 'nv' linux driver but the closed source nvidia driver sucks for latency.

sam

[Continuing along this line, I put an Nvidia Riva TNT board in the computer, and ran it for a while. I was getting jitter of 10561/11695, which sounds quite good. Much better than the Intel 810 video.

Anyway, I'm stuck at 800x600 resolution. I have downloaded the Nvidia legacy driver for this card, but it required you to have net access and NOT be running X to install it. I usually just type "init 3", but apparently the Ubuntu 8.04 default runlevel IS 3, instead of the more usual 5. I can go to runlevel 1, but then the net, etc. is down. Going even to runlevel 2 brings up X. So, is there a way to set the OS so it is fully up, but not running X?

One curious thing, this motherboard had a little card plugged into the AGP slot with 2 Nanya memory chips, the card says "smart" and "aimm-133" on it. I'm guessing this is a video memory that maybe relieves the graphics load on general system memory. I removed this to put in the Nvidia card.

Thanks,

Jon

[jmelson]

I think people have had luck with the 'vesa' and 'nv' linux driver but the closed source nvidia driver sucks for latency.

sam

OK, well, then I ought to stick with "nv", but I need to get the video settings changed. I tried editing the Xorg.conf file a couple times, but it didn't seem to take effect. There was a video selection dialogue that came up the first time I booted with the new board, do you know what that dialogue is and how to start it from the command line?

I've done this video mode editing before, but Ubuntu is different, and I can't figure out where the files are.

Thanks,

Jon

[acondit]

OK, well, then I ought to stick with "nv", but I need to get the video settings changed. I tried editing the Xorg.conf file a couple times, but it didn't seem to take effect. There was a video selection dialogue that came up the first time I booted with the new board, do you know what that dialogue is and how to start it from the command line?

I've done this video mode editing before, but Ubuntu is different, and I can't figure out where the files are.

Thanks,

Jon

Have you tried "displayconfigGTK"? You may have to find it and install it, I think that I got it off of the regular 8.04 liveCD.

Alan