Wow thanks, Charles!  Never heard of Zero-MQ, totally diving into the 
material now! :)  Also reading into haltalk so I can better understand how 
it works.

Hopefully I can learn enough to contribute meaningfully to the project!  
Thanks again!

On Tuesday, September 18, 2018 at 8:29:29 AM UTC-5, Charles Steinkuehler 
wrote:
>
> On 9/17/2018 10:07 PM, Joshua Dickerson wrote: 
> > 
> > My naive approach would be to have a registry of output signals which 
> > includes which MCU each actually resides on.  So if a particular HAL 
> > component task is reading a signal that's already on the MCU it's 
> running 
> > on, it's immediately returned- otherwise it pulls the data over a 
> network 
> > layer (which could shared memory bus, RS485, ethernet, etc.)  Is there 
> > something out there that does this?  Maybe some kind of mutant hybrid 
> > between HAL/NML/SCADA? 
> > 
> > Of course this complicates things over simply using pointers to a single 
> > shared memory space.  I also get the sense the linuxCNC group balks at 
> this 
> > kind of idea, they want to keep it all on one machine in the interest of 
> > latency anyway.  Just searching various machine controller project 
> > communities for where this kind of idea might be interesting.  I would 
> > really like something like a Raspberry Pi tied into a MCU which does all 
> > the hard-RT/IO stuff, but not quite in the way Klipper does it.  Klipper 
> > basically sends commands to be followed at some specific time stamp.   
> > That's actually pretty cool, but I want something that allows for more 
> > feedback and flexibility between the various systems.   
>
> Look into the haltalk stuff using Zero-MQ messaging.  It was 
> specifically written to enable connecting various HAL "islands" which 
> may or may not have a shared memory space.  The messaging protocol is 
> transport agnostic, so you can setup HAL nodes that communicate via 
> shared memory, Ethernet, serial, or whatever. 
>
> The existing haltalk may not do everything you want, but it's probably 
> the best place to start: 
>
> https://machinekoder.com/machinetalk-explained-part-4-hal-remote/ 
> <https://www.google.com/url?q=https%3A%2F%2Fmachinekoder.com%2Fmachinetalk-explained-part-4-hal-remote%2F&sa=D&sntz=1&usg=AFQjCNH96U0D-4z_1Ww4nN3Dq9Os9RRpNw>
>  
>
> -- 
> Charles Steinkuehler 
> cha...@steinkuehler.net <javascript:> 
>

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