Raspberry Pi 4 - USB not working under LinuxCNC

Ok & thanks Andy.
Playing around with the RasPi is quite fun, a lot of fun. A few days ago, I decided to give this platform a serious try and I must say, so far I am very happy with it. I want to use it as a "clonable" CNC controller platform i.e., quickliy recplicate and set-up additional machine controllers - we will see Along the first set-up steps, I experienced that the RasPi also serves quite well as an "update" free (at least I have control over it), low power (environment), zero fan noise (quiet office/living), and no personal data bleeding platform.

Again, thanks for sour support!

Stefan, Germany.

From a professional/industrial perspective, I'm completely sold on Pis. We did an emergency replacement of £400 'industrial' x86 boards that were too slow to calculate new certs for contactless card processing. We fitted the Pis with industrial 4Gb SD cards (that cost more that the Pis) and >4 years on, we have yet to have a failure in a pretty harsh environment.
As I said to our customer, if they can survive school children, they can survive anything.

I've got 2 of them and once I worked out how to install preempt-rt, the 64 bit Pi4b has latency for Lcnc is very good but for me  they are of limited use because of the inability to install VTK so I can use QTpyvcp and QTvcp GUI's and also I was unable to install ethercat. I'm a bit dissappointed about that! 

Rod,

do you/did you use them to control your Plasma table ... or any other setup?
If so, what kind of HW/controller setup was employed?

Reason for asking - I am interested in your (latency) experience using the RasPi standalone, directly connected with e.g. stepper driver via its GPIOS, or in combination with Mesa cards inbetween to take over the intensive control work. Clearly, RasPi standalone would be great (less HW/cost). I am planning on using them as a low cost CNC controller primarily for mill, lathe and plasma applications.

Thanks.

I did not buy these for linuxcnc controllers.
I just wanted to try them out with recent advances.
I was able to install Debian Bullseye Pi OS 64 bit
I was able to install the PREEMPT_RT patch by following some Pi howto on the net.
I was able to install QT5
I was unable to install VTK.
I was expecting to  be able to install ethercat from  a unofficial repository per this method as the pi is supported in their builds:
forum.linuxcnc.org/ethercat/45336-etherc...-how-to-step-by-step
But it did not work for me.

After 2-3 days tag wrestling the two I moved on.
I've had much more luck with USFF PC's and find the J1900/J1415  industrial fanless PCs on Aliexpress. They come with twin ethernet NICs and twin serial ports (for RS485)

I have not run any cnc gear with the pi as I never got that far using the later operating systems. But the latency is not much different to the J1900's so I'm sure they would work OK if you don't need to run. If the VTK issue was solved, I could find a use for them

Thanks Rod for the quick response!

I quickly looked into Qt5 (GUI?) & VTK (Visualizer). Seems to be less an issue for my use case i.e., using the RasPi mainly as a CNC controller together with Axis and maybe a simple self-developed GUI. Although, since I got two of them a few days ago, I started using them in my office for Internet and Email because of the positive experience I have with them (that doen't mean everything works flawless . My goal is to reduce time spent on my noisy Windows machines to a minimum. Lets see where thie leads to ...

Stefan