What you want to do is perform a topological sort (man tsort) on the graph.

It should be simple enough to write a tool to do that.

Ken


On 12/14/2013 12:18 PM, Gene Heskett wrote:
> On Saturday 14 December 2013 11:38:26 Marius Alksnys did opine:
>
>> Thanks, I will try it.
>> This is something what I was thinking about and even tried to swap pid
>> and offset addf lines, but I never found importance of addf order in
>> documentation, which would be worth noting there..
> It is important. In both threads.
>
> General rule of thumb in base thread,
> addf anything that needs a sample from hdwe (encoder?)
> addf in order, the chain of non-fp stuff the sample flows through
> addf last (for steppers) the parport.N functions
>
> General rule of thumb for servo thread speed stuff:
> addf signal receiver FP stuff (such as an encoder)
> addf the module its "net" output goes to
> addf next module the "net" of the above goes to
> addf continue till this function is completed
>
> That way any changes in the signal are propagated thru the processing chain
> in a single servo cycle.  And when the actual control outputs are updated,
> they are working with the most up to date data they can get.
>
> There are times I expect when you may have another function chain that
> needs to be interleaved with the above, but I haven't run across a case
> where I could test and get a demonstratable advantage. YMMV of course.
> Spindle control servos, based on an encoders velocity, will get very
> unstable if the path is backwards thru the addf's because this severely
> restricts the bandwidth of the control.  Even with what I THINK is all the
> ducks in a row, I found that double the speed of the servo thread from 1
> millisecond to .5 milliseconds was a huge improvement.  Because of non-
> linearity in the pwmgen and controller, I have a linear module between the
> PID.out and the PWMGEN.in, additional time delay, but it sure tames the
> PID.error range.  Decent load torque at creep speeds (50 rpms) without
> hunting at 75% speeds (1200 on up) where its very sensitive.
>
> In retrospect, and I'd have to make additional room for it now, I know I
> would have been schmardter to have used the PMDX-106 (or whatever is being
> sold for that now) in place of the cheaper, too darned cheap and slow &
> needs modification to raise its control bandwidth if its anywhere in a
> feedback chain, CNC4PC C41 for that translation function.  Dumb, but its
> done.  I won't make that mistake again, it, out of the bag, is simply not
> suitable for use in a servo controlled environment.  You have been
> warned...
>
>> On 2013.12.14 13:12, andy pugh wrote:
>>> On 14 December 2013 08:08, Marius Alksnys <marius.alks...@gmail.com>
> wrote:
>>>> I tried simple configuration (without offset component) too. And it
>>>> worked perfectly.
>>> If it goes wrong with the offset component but works without it, then
>>> I suspect that the problem is with the execution order of the motion
>>> controller and the offset component.
>>> If you change the sequence of the "addf" statements in the HAL then
>>> you can probably make it work.
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>
> Cheers, Gene

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