”emcmotController（）“
10 Mar 2015 20:25 #56616
by socrassi
”emcmotController（）“ was created by socrassi
Hi:
I'm reading the source code of the LinuxCNC.
As showed above, the function emcmotController() is called at regular intervals,..But i cannot find the caller loop anywhere..
is there anyone knowing where's the caller loop to emcmotController()???
Best regards.
I'm reading the source code of the LinuxCNC.
As showed above, the function emcmotController() is called at regular intervals,..But i cannot find the caller loop anywhere..
is there anyone knowing where's the caller loop to emcmotController()???
Best regards.
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10 Mar 2015 21:22 #56623
by andypugh
It is called by the realtime system in the servo thread.
If you look in your HAL config you will see (typically)
Which calls the module specified in the INI file [EMCMOT] section every SERVO_PERIOD.
(This is actually a bit untidy, as really emcmot has no business _starting_ the realtime threads)
Replied by andypugh on topic ”emcmotController（）“
is there anyone knowing where's the caller loop to emcmotController()???
It is called by the realtime system in the servo thread.
If you look in your HAL config you will see (typically)
loadrt [EMCMOT]EMCMOT base_period_nsec=[EMCMOT]BASE_PERIOD servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[TRAJ]AXESWhich calls the module specified in the INI file [EMCMOT] section every SERVO_PERIOD.
(This is actually a bit untidy, as really emcmot has no business _starting_ the realtime threads)
The following user(s) said Thank You: socrassi
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10 Mar 2015 21:23 #56624
by dgarrett
see motion.c init_threads()
Replied by dgarrett on topic ”emcmotController（）“
$ find . -type f -iname '*.c' -exec grep -H emcmotController {} \;
./emc/motion/control.c:* emcmotController() is the main loop running at the servo cycle
./emc/motion/control.c: emcmotController() runs the trajectory and interpolation calculations
./emc/motion/control.c:void emcmotController(void *arg, long period)
./emc/motion/motion.c: retval = hal_export_funct("motion-controller", emcmotController, 0 /* arg$ halcmd show funct
Exported Functions:
Owner CodeAddr Arg FP Users Name
...
00021 b734d943 00000000 YES 1 motion-command-handler
00021 b7350979 00000000 YES 1 motion-controller
...see motion.c init_threads()
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11 Mar 2015 07:25 #56657
by socrassi
Replied by socrassi on topic ”emcmotController（）“
Thank you.
There's some stuff i cannot understand.
Is there no codes written to explain the loop caller to emcmotController() ?
or just uses a "loadrt"? how do the "loadrt" work??
is there no relation with the function of init_threads() or hal_export_funct() in motion.c?
There's some stuff i cannot understand.
Is there no codes written to explain the loop caller to emcmotController() ?
or just uses a "loadrt"? how do the "loadrt" work??
is there no relation with the function of init_threads() or hal_export_funct() in motion.c?
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11 Mar 2015 15:54 #56661
by andypugh
That is the whole basis of the Realtime system.
Consider a simple HAL component:
git.linuxcnc.org/gitweb?p=linuxcnc.git;a...24c4e0800617;hb=HEAD
This is a very short comp that doesn't do anything that needs to be done any more, but makes a simple example.
Line 199 contains a call to "hal_export_funct()" which defines "update_supply()" as a realtime function.
Then, in the HAL file "loadrt update_supply" adds a pointer to the "update_supply()" function to the calling list.
When the realtime system is started then exactly every servo-period every function in the calling list is run once in strict sequence
So there isn't an outer-loop as such. It is more like an interrupt-driven system, with time-based interrupts.
Replied by andypugh on topic ”emcmotController（）“
Is there no codes written to explain the loop caller to emcmotController() ?
or just uses a "loadrt"? how do the "loadrt" work??
That is the whole basis of the Realtime system.
Consider a simple HAL component:
git.linuxcnc.org/gitweb?p=linuxcnc.git;a...24c4e0800617;hb=HEAD
This is a very short comp that doesn't do anything that needs to be done any more, but makes a simple example.
Line 199 contains a call to "hal_export_funct()" which defines "update_supply()" as a realtime function.
Then, in the HAL file "loadrt update_supply" adds a pointer to the "update_supply()" function to the calling list.
When the realtime system is started then exactly every servo-period every function in the calling list is run once in strict sequence
So there isn't an outer-loop as such. It is more like an interrupt-driven system, with time-based interrupts.
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11 Mar 2015 18:09 #56664
by socrassi
Replied by socrassi on topic ”emcmotController（）“
Thank you. I see. You are so enthusiastic.
There are two "addf .. to servo thread' in the *.hal file after the "loadrt" sentence..That’s where the emcmotController () function added to the servo thread.
Regards.
There are two "addf .. to servo thread' in the *.hal file after the "loadrt" sentence..That’s where the emcmotController () function added to the servo thread.
Regards.
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