Hal Setup for External Homing with Servo Drive Control

Dear all,

I am currently thinking about a setup with a slightly different homing approach to make use of the servo driver's ability to home itself. While this appears to be non-sense for a regular axis, it is potentially desirable to make use of the specific driver's gantry synchronization features. The drives in question are Delta ASDA-A2.

What we are trying to do is the following:
-Have linuxCNC initiate homing through some DO, I guess "joint.N.homing" would be a suitable pin
-Have the drive do its thing
-Have the drive report out that homing was completed : Question: How do I get this signal to linuxCNC? How do I set up homing, up so that linuxCNC can cope with external homing?
-Have linuxCNC signal the drive that all axis are homed and that they may switch modes from PR to PT (PR: drive can home itself, but can only move to predefined positions, PT drive accepts typical motion signals via step/dir)

Any ideas?

IF the drives are CIA402 ethercat compatible, yes, you can use them. There is a CIA402 component and uses the home to index function.
Check the instructions document in my repo
github.com/rodw-au/linuxcnc-cia402

This needs some updating as I am close to completing my configuration.

Note people have ben bale to home to index with this method but I was unable to home to a home switch using the drives features.

Dear Rod,

thanks for getting back to me.
No, the drives do not speak EtherCAT.

The setup of the drives appears to be working (at least for a single axis for now). My questions really just relate to making this work with linuxCNC using conventional IO.

From what I tried using a modified version of this component
github.com/dbraun1981/hal-cia402
I think you will need a similar component to ensure the position error that will occur when th eencoder is reporting without linuxcnc commanding the drive.

I think you also will need to modify homing.c

I reverted to linuxcnc homing which supports gantry homing simply by setting HOMING_SEQUENCE = -1 on the gantry joints in the ini file

I see what you are pointing at. Modifying homing.c certainly is out of my league. The pointer to using encoders (hadn't even mentioned those) is quite a valid one. Technically, the encoders could also be integrated with the drives directly.

I currently use the linuxcnc gantry setup and it works well. Delta ASDA-A2 has a special mode to ensure synchronous motion between two drives by master-slaving them. In this mode they operate of one step/dir interface and maintain their relative position. Furthermore, it would allow the use of a single linear encoder instead of two. I would like to work out if I can make use of this feature. Hence my questions:).

Side question (because I currently can't try): Is it possible to net the signals of one (linear)  encoder to two step-gens?

@Mods: Maybe move to advanced config?

rodw wrote:

IF the drives are CIA402 ethercat compatible, yes, you can use them. There is a CIA402 component and uses the home to index function.
Check the instructions document in my repo
github.com/rodw-au/linuxcnc-cia402

This needs some updating as I am close to completing my configuration.

Note people have ben bale to home to index with this method but I was unable to home to a home switch using the drives features.
 

Is it also possible with CanOpen Delta drives and Beckhoff EK1100/EL6751? I'm using the A2-M for a YY-spindle setup.

Best regards,
Pierre

Hello Rod. I was following step by step the instruction you gave, and after using halcompile to cia402 i got:

cnc@cnc:~/dev/ec-debianize/hal-cia402$ sudo halcompile --install cia402.comp
sudo: halcompile: command not found

I don't know where can be a mistake, because when i configured uspace, i got:

cnc@cnc:~$ cd dev/linuxcnc/debian/
cnc@cnc:~/dev/linuxcnc/debian$ ./configure uspace
uspace is accepted for compatibility, but ignored
successfully configured for 'uspace-Debian-10'..

I'd be very glad if you will help me to solve this problem




 

If you have built debs from source, there should also be a .deb file called linuxcnc-uspace-dev which needs installing.
should be in your ~/dev folder?
RIP builds will have it but don't need sudo