How to select Driver Boards?? - Design Considerations?

irakandjii wrote: Thanks Andy. It is nice to hear the stuff is supported BUT...
Are there any specifics documented anywhere?

Another option is the Pico Systems (disclosure - my company) PWM controller for servos and the Universal Stepper Controller for anything that needs step and direction. It can run those in either open-loop or closed-loop mode. These are controlled by the parallel port as a communications channel to the device. Drivers are included in the LinuxCNC distribution.

Jon

BTW .. I would not use a raspi as a front end so it never occurred to me, I use a lot of them, but never for mission critical stuff.

My understanding is that LinuxCNC will run on a RPi, but it's not capable of usable performance yet. At this stage it's more of an academic exercise to prove it can be done than an actual working solution. Other more knowledgeable folk may be able to correct my assumptions, but that's certainly the way it seems from the information obtainable here and elsewhere on the net.

PCI is fairly mature technology, but I don't see any indication that it is an endangered species yet. Mesa cards and similar (even PCI parallel port cards) are still likely to be the go-to option here for years to come.

Step/dir motor drivers are plentiful, capable and cheap. Your only real design decision here should be how to interface LinuxCNC with them.

irakandjii wrote: The first part was a request for a link to where I can find design information.

I think my problem is that I am not sure what you want help designing.

On PCI we might be talking about the same thing. When I reference DB25 I was talking about a MESA PCIe card with a DB25 connecting to a daughter card.

Both Pico and Mesa make very capable interface boards that use the parallel port as a communications bus. I assumed you were meaning one of these. (Pico USC and PPMC and the Mesa 7i43 and 7i90 I assumed you were talking about these, from the context.

And then there is always the option of using the parallel port as GPIO, which is almost always the cheapest option, and can work very well if the machine does not require much GPIO.

Ah ok on the 2.8 build, I am using the GIT master for source. Is this buildbot master build the same or different?
I used the instructions on the site to get the release from GIT, so now I am confused regarding the official release site.

The buildbot builds all the current versions, both 2.7 and master. master and "2.8" are the same thing.

These buildbot files seem to only support precise. Am I reading that wrong?

Yes, you are reading it wrong.
buildbot.linuxcnc.org/
Precise, Wheezy, Jessie, Stretch, Lucid are all built, and on a variety of platforms (including armhf)

But the official release is 2.7.14 at the moment. This is available as a convenience on Debian Wheezy (RTAI) and Debian Stretch (preempt RT) but that is in no way meant to indicate that other distributions and platforms are not supported. If you want to use Bionic on an ARM using the Xenomai realtime then it ought to work, but you will need to compile it yourself.

andypugh wrote: (Pico USC and PPMC

Just to clarify for the future, Pico Systems makes THREE different controllers for motion control, that are all interfaced through the parallel port. The Universal Stepper Controller produces step and direction outputs, can optionally use encoder feedback on any or all 4 axes, and provides 16 digital inputs and 8 SSR outputs.

The PWM controller is similar to the Stepper controller, but provides PWM outputs to drive digital-input servo amps. Pico Systems also makes servo amps for brush and brushless motors to go with this controller. See :
pico-systems.com/osc2.5/catalog/index.php?cPath=3
for more info on these products.

Finally, the PPMC is a set of boards to interface to analog-input servo amps. You can plug additional boards into the motherboard to expand the number of inputs and outputs.

Jon