Re: [Emc-users] Reading config values with a realtime HAL module.

[andy pugh]

On 5 July 2017 at 12:14, Les Newell  wrote:
> The next question, is it possible to repeat sections? For instance in
> [RS274NGC] I have different parameter files for each config. All other
> values are the same. It would be nice to have a [RS274NGC] section in my
> main config to specify the parameter file and another [RS274NGC] section in
> my inc file to specify everything else that is common between the two
> configs

I don't think so, but it's an easy experiment.

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Re: [Emc-users] Reading config values with a realtime HAL module.

[Les Newell]

Thanks Andy, I was going to ask if there was an include function for ini 
files. My lathe runs two configs, one with the tool turret installed and 
one without. My turret is tiny and only suitable for a few jobs. It is 
so small it can be mounted on one of the QC tool holders. Currently I 
run two separate ini files but it would be much better to stick all of 
config values that are common into an inc file.


The next question, is it possible to repeat sections? For instance in 
[RS274NGC] I have different parameter files for each config. All other 
values are the same. It would be nice to have a [RS274NGC] section in my 
main config to specify the parameter file and another [RS274NGC] section 
in my inc file to specify everything else that is common between the two 
configs. To be honest this is purely icing on the cake. Just having 
#INCLUDE makes a big difference. Repeating a few sections is not a real 
problem.


As far as the original question goes, I probably won't bother with the 
kinematics module. I spent a day on the machine, realigning the spindle 
and generally going through the machine and readjusting everything. The 
error is a lot smaller now and realistically within the limits of 
anything I normally want to make. I'm surprised how good it is 
considering this machine spent most of it's life with a non-functional 
lube pump. As far as I can tell someone forgot to fit the foot valve 
ball when they originally assembled it!


Les

On 05/07/2017 11:42, andy pugh wrote:

  of a kludge, but the streamer/ halstreamer system could do what you are 
describing.
Another way:

INI files can use #INCLUDE
http://linuxcnc.org/docs/2.7/html/config/ini-config.html#_include_files

{.ini file}
[KINS]
#INCLUDE corrections.inc
...

{.inc file}
ZVALS = 0,10,20,30,40,50,60,70
XVALS = 0,0.1,-0.3,0.7...

{.hal file}
loadrt mykins zvals=[KINS]ZVALS xvals=[KINS]XVALS




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Re: [Emc-users] Reading config values with a realtime HAL module.

[andy pugh]

On 5 July 2017 at 02:43, John Kasunich  wrote:
> Kind of a kludge, but the streamer/ halstreamer system could do what you are 
> describing.

Another way:

INI files can use #INCLUDE
http://linuxcnc.org/docs/2.7/html/config/ini-config.html#_include_files

{.ini file}
[KINS]
#INCLUDE corrections.inc
...

{.inc file}
ZVALS = 0,10,20,30,40,50,60,70
XVALS = 0,0.1,-0.3,0.7...

{.hal file}
loadrt mykins zvals=[KINS]ZVALS xvals=[KINS]XVALS

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lunatics."
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Re: [Emc-users] Reading config values with a realtime HAL module.

[John Kasunich]

Kind of a kludge, but the streamer/ halstreamer system could do what you are 
describing.
The component that wants to use the data would export a clock pin and one or 
more input pins.
Each edge of the clock pin delivers a value (or set of values) from an external 
file.

In this application, it would only be clocked during startup. Once the 
necessary data is transferred the streamer part (realtime) would sit idle, and 
the halstreamer part (user space) would terminate.

http://linuxcnc.org/docs/html/man/man9/streamer.9.html
http://linuxcnc.org/docs/html/man/man1/halstreamer.1.html


On Tue, Jul 4, 2017, at 01:28 AM, Dave Caroline wrote:
> For probe compensation batch reading would be far more useful than compiled 
> in,
> then it becomes simple to read the compensation file for any stylus
> you change too.
> 
> Dave Caroline
> 
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Re: [Emc-users] Reading config values with a realtime HAL module.

[Dave Caroline]

For probe compensation batch reading would be far more useful than compiled in,
then it becomes simple to read the compensation file for any stylus
you change too.

Dave Caroline

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Re: [Emc-users] Reading config values with a realtime HAL module.

[andy pugh]

On 3 July 2017 at 13:59, Les Newell  wrote:
>
> On my lathe I will probably keep with using kinematics as it is then before
> backlash compensation rather than after.

It seems likely to be a very simple kinematics module, and so will
probably compile easily with halcompile.
At that point it might be pragmatic to simply store the offset data
hard-coded into the kins module.

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designed for the especial use of mechanical geniuses, daredevils and
lunatics."
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Re: [Emc-users] Reading config values with a realtime HAL module.

[Les Newell]

On 03/07/2017 13:15, andy pugh wrote:

There is a HAL module for that:
http://linuxcnc.org/docs/devel/html/man/man9/offset.9.html


So I see. I missed John's original link to the offset module. Doing 
something similar to  that worked on my lathe but I did have some homing 
issues. That was on a very old version of LinuxCNC so homing may handle 
it better now.


On my lathe I will probably keep with using kinematics as it is then 
before backlash compensation rather than after.


Les

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Re: [Emc-users] Reading config values with a realtime HAL module.

[andy pugh]

On 3 July 2017 at 11:16, Les Newell  wrote:
> You need to go both ways. You need to offset the command and do a reverse
> offset on the feedback.

There is a HAL module for that:
http://linuxcnc.org/docs/devel/html/man/man9/offset.9.html

Or there is an exerimental branch with the option built-in
https://github.com/LinuxCNC/linuxcnc/commit/08ca67aa0efb5c32b2f17032810d406face2b7c3

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Re: [Emc-users] Reading config values with a realtime HAL module.

[Les Newell]

Hi Andy,


Putting the Z axis position into the input of "lincurve" could give
you an output to apply as an offset to the X position command.


You need to go both ways. You need to offset the command and do a 
reverse offset on the feedback. Yes, I could use the generated offset 
then add extra modules to do the addition and subtraction but it all 
gets a bit messy. That is pretty much how I used to do it, though I 
stuck everything in one module. However this is exactly what kinematics 
are made for so it makes sense to use them.


Les

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Re: [Emc-users] Reading config values with a realtime HAL module.

[andy pugh]

On 2 July 2017 at 09:07, Les Newell  wrote:
> The problem is that bed wear or spindle misalignment causes cross-coupling
> between the X and Z axes, which is why it needs to be done in kinematics.


Putting the Z axis position into the input of "lincurve" could give
you an output to apply as an offset to the X position command.

-- 
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lunatics."
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Re: [Emc-users] Reading config values with a realtime HAL module.

[Les Newell]

By ugly I was talking about setting up shared memory communications 
simply to pass config values once at startup. It is also untidy from 
the user's viewpoint. They need to load two modules even though one is 
going to simply read from a file, squirt those values to the HAL 
module then exit.




After looking though the docs I found this in comp:
/option userinit yes/ - (default: no) This option is ignored if the 
option /userspace/ (see above) is set to /no/. If /userinit/ is 
specified, the function /userinit(argc,argv)/ is called before 
/rtapi_app_main()/ (and thus before the call to /hal_init()/ ). This 
function may process the commandline arguments or take other actions. 
Its return type is /void/; it may call /exit()/ if it wishes to 
terminate rather than create a HAL component (for instance, because the 
commandline arguments were invalid).


This is exactly what I am after. It runs in user space so I can grab the 
table from a file before the module starts running in HAL space. I was 
sure something like that had to exist internally but it is nice to know 
it is easily available.


Les
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Re: [Emc-users] Reading config values with a realtime HAL module.

[Les Newell]

Hi John,

The problem is that bed wear or spindle misalignment causes 
cross-coupling between the X and Z axes, which is why it needs to be 
done in kinematics.


Les

On 02/07/17 01:47, John Kasunich wrote:
How many points do you need? If 16 or less, check out the lincurve 
component

http://linuxcnc.org/docs/html/man/man9/lincurve.9.html




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Re: [Emc-users] Reading config values with a realtime HAL module.

[John Kasunich]

On Fri, Jun 30, 2017, at 05:46 PM, Les Newell wrote:
> Is it possible for a real time HAL module to read config values from 
> disk? I guess I could do it the ugly way and have two modules, one in 
> user space to read the disk and pass values to the mealtime module.
> 
> My lathe is pretty worn near the headstock so it tends to turn tapers 
> when working near the chuck. I want to write a kinematics module to 
> compensate for this taper, basically adding an offset to X depending on 
> the Z position. To do this I need to pass values to the kinematics 
> module in a similar way to leadscrew compensation.
> 
> In the previous setup I had a simple kinematics-ish module just before X 
> PID but it was a hack and didn't work very well, with all of the values 
> hard coded. It also did ugly things when homing.
> 
> Les

How many points do you need?  If 16 or less, check out the lincurve component
http://linuxcnc.org/docs/html/man/man9/lincurve.9.html

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Re: [Emc-users] Reading config values with a realtime HAL module.

[Les Newell]

On 30/06/17 23:05, Chris Albertson wrote:
That is not "ugly" is the common why things are done in real-time 
systems.

   You try as hard as you can to push everything you can into user space.

What you describe is actually "best practice".

Look even at the normal Linux kernel.  Typically an interrupt handler might
read data off the interface then flip a bit and that's it.  Processing the
data happens in a user space task.   Very common design pattern used over
and over.




I'm not talking about file I/O while running in real time. The task is 
started from user space so at startup you have access to user space. 
That is how command line config values are passed to the real-time task. 
I was hoping there would be some way to make use of that to load config 
values from a file instead of the command line.


By ugly I was talking about setting up shared memory communications 
simply to pass config values once at startup. It is also untidy from the 
user's viewpoint. They need to load two modules even though one is going 
to simply read from a file, squirt those values to the HAL module then exit.



I'm doing other work right now in a different area (not MK) and I'm using a
full on actual RTOS (Not Linux based) and a common structure I use is the
"work queue" I'll do minimum processing in the real time task then place a
task on the queue.  Then background non-real time tasks pull work requests
off the queue.   This is the "Computer Science 101" text book design that
was like used back in the 1950's


Of course you keep the real-time task as lean as possible. I'm fully 
aware of that and have also done plenty of RTOS stuff. I've even written 
my own cooperative + preemptive real-time multi-tasking OS for one 
project where space and cpu were so constrained no off-the-shelf RTOS 
would work. That one raised a few eyebrows when I wrote it in C++. A lot 
of people think C++ is more bloated and slower than C but it all comes 
down to how you use it.


Les


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Re: [Emc-users] Reading config values with a realtime HAL module.

[Chris Albertson]

On Fri, Jun 30, 2017 at 2:46 PM, Les Newell 
wrote:

> Is it possible for a real time HAL module to read config values from disk?
> I guess I could do it the ugly way and have two modules, one in user space
> to read the disk and pass values to the mealtime module.
>

That is not "ugly" is the common why things are done in real-time systems.
  You try as hard as you can to push everything you can into user space.

What you describe is actually "best practice".

Look even at the normal Linux kernel.  Typically an interrupt handler might
read data off the interface then flip a bit and that's it.  Processing the
data happens in a user space task.   Very common design pattern used over
and over.

I'm doing other work right now in a different area (not MK) and I'm using a
full on actual RTOS (Not Linux based) and a common structure I use is the
"work queue" I'll do minimum processing in the real time task then place a
task on the queue.  Then background non-real time tasks pull work requests
off the queue.   This is the "Computer Science 101" text book design that
was like used back in the 1950's




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Re: [Emc-users] Reading config values with a realtime HAL module.

[Sebastian Kuzminsky]

On 06/30/2017 03:46 PM, Les Newell wrote:

Is it possible for a real time HAL module to read config values from
disk? I guess I could do it the ugly way and have two modules, one in
user space to read the disk and pass values to the mealtime module.


Realtime modules can not do file I/O.

If you have only a few (up to maybe a few dozen?) values to pass in, 
consider using HAL pins set from INI variables at load time.



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