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Latency excursions beyond the visible graph area.

and what does this mean? thanks

same values or i am wrong??

Note the missing spikes (colored in blue/red) at the extreme left and right of the graph.

or a 7i92... i payed for both cards 100 euros...

so for my information... on a normal pc like optiplex 3020m or lenovo m73 tiny.. i have latency under 2000... but i never looked this way in the histogram.

can you explain me the spike?! please

Assuming you use the 7c81's FGPA for stepgen and don't sofware step, you don't need a base thread so latency requirements is much relaxed. I'd be happy with anything under 130,000 with 200,000 at a pinch

on ny m73 i have a jitter of 1000... so what is the reason thst you say that this latency is good???? thanks

Raspberry Pi 5 CNC Configuration Software Raspberry Pi 5 has much stronger performance than Raspberry Pi 4, and runs LINUXCNC software very smoothly. It is often difficult for enthusiasts to configure themselves. I have written this software, which allows users to simply fill in Raspberry Pi GPIO pins and export HAL files directly. Welcome to try it out. 

Your latency is a pass, move on

Much better, move on to wiring and making chips!
Keep an eye when starting LinuxCNC if it complains about latency, it shows a warning usually when enabling it or later during use.

same values or i am wrong??


 


thanks

I forget 1 thing.. i use a 64gb micro sd card from the brand kexin from amazon.

amzn.eu/d/hXGglyV

try this

Hi guys!I am on a new Project and found a mesa 7c81 an 7i92 on the flewmarket... dont know why someone sell it on a flewmarket...i start reading about the 7c81 and look to my boxes and found a raspberry pi 4 b version with 8gb ram.. oki load the image for the sd card from the linuxcnc website and bring it up.i isolate cpu 1 2 3 but latency doesnt go down.

Any tips?
in the config i disable audio blueetooth and overclock to 6v and 2000mhz..

which information i can share to get the cow frome the ice?

thanks all


 

 

 

Just my take on it. There are many ways to run linuxcnc, keep that in mind.

My questions:
* What should I run LinuxCNC on?  I've got a spare RPi 4 sitting in my drawer.  I've got a couple of Supermicro Intel Atom-based ITX server motherboards lying around.  What's the most intelligent way to go?

Atom is probably below the acceptable performance limit, but anything faster than that. There are some new mini-ITX main-boards with N100 integrated. CPU performance is more for the user experience, the later HMIs (or guis) may need a bit faster CPU, while the old Axis works with anything. For the cnc part it is about real-time jitter and there usually are ways to tweak settings to come to low jitter. I go with N100 nowadays, but its just one of many possibilities. Once you have seen the newer guis you will want to use one of those. And need at least some CPU performance. I ran on RPi4, I would think a step up to RPi5 would be nice.

* It seems that a parallel port interface is the "old-school" way of doing things.  Now, it seems that most prefer an Ethernet interface.  Is there a disadvantage of going one way or another?

Stepper performance (steps/seconds), number of IOs, and other types of IO than digital IO is what makes people move away from the parallel port. Plus that main-boards nowadays seldom have a parallel port and need to have one added.

* Since I have to replace the steppers anyway, is it foolish to go with a "traditional" setup rather than Ethercat?  It seems like Ethercat will be considerably more expensive (like twice the price or more) - but is it worth the price?

You won't get anything extra from the milling machine using EtherCAT. It is a different way of doing the same thing.

* Everyone seems to agree that Mesa boards are the "gold standard."  How do Pico Systems' boards compare?  Jon Elson lives like 20 miles from my house.  Does anyone have experience with his customer service?  Is it foolish to consider anything other than a Mesa?

From what I can see, and I may be wrong, the Pico Systems' board connect to the parallel port? If you go with a parallel port solution that can work. Mesa's board on the other hand typically use EtherNet, SPI, PCIE, or PCI (and maybe more) to connect to the computer. This gives speed and reliability.

* If I go with a Mesa setup, which direction should I go?  If I use the RPi, I could go with the 7C80 or 7C81 - I could also run an Ethernet setup.  If I use the server motherboard, I could go with a parallel port setup or an Ethernet setup.  Is there an advantage of going one way or another, here?

I've only used Ethernet setup and see few reasons to do anything else. If you are only ever to use Raspberry one can think of the 7C line. I would like to keep all options open as far as possible.

* If I go with a given Mesa board, what else will I need to buy?  It seems that some of the Mesa cards (like the 7C80 and the 7I95T) will hook directly to the stepper drives, while others require a separate daughter card (BoB)?

Send Mesa a mail with those questions, they are usually very happy to help. For a normal stepper motor system I would look at 7i96, which connects to the stepper driver with the step/dir/enable signals.

* What hardware (if any) would I need in order to use the encoders on the steppers as a DRO?  Will any of my hardware selection above affect my ability to have this feature?

For Mesa to answer, I think you are looking at a 7i85. From what I understand, encoder counting is done by the FPGA, so the card must either do it itself on the FPGA board, or have a connector that allows a daughter board to connect the encoder inputs. The 7i96+7i85 does that.

* Will a cheap Amazon/Aliexpress stepper motor/drive/power supply set work, or will I need to buy the stepper drives separately?  If I need a particular stepper drive, should I go with a Gecko or something else?

Yes, will work fine, just size it to suit the stepper motors. I have good experience with such stepper drives.

* If I run a touchscreen and a pendant, is there any reason why I will need a keyboard hooked up to this machine (once it is configured)?

Depends on the gui and how well touch screen input is integrated. For example, I run the qtdragon gui and there the keyboard input is well integrated. Except when I need to edit the G-code file, then I bring in the keyboard. Normally I have it tucked away though.

Perhaps the Raspberry Pi can be connected to the stepper drivers directly (via the GPIO header).

Why would you replace the steppers?

The old ones might work just fine.

Brushless motors should last almost forever (like 1000 years or so).

There is no reason a brushless motor should break or degrade.


Before you do anything, you should really give that poor old machine a good cleaning and then grease/oil moving parts and spray WD-40 over stationary exposed metal pieces to prevent rust.

Remember that most induction motors need to be relubricated every 10 years of normal service.