stuck attempting to get multi-motor axis set up on 7I96S using mesaCT

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10 Jun 2022 09:45 - 10 Jun 2022 12:12 #244856 by Gruntled Raptor
Y-axis has two stepper motors in parallel. Created working config for single motor using mesaCT on 2.8 master (keeping things simple while i work everything out). Attempted to follow steps outlined on

forum.linuxcnc.org/49-basic-configuratio...c-2-8-master?start=0

However, my Hal file is completely unrecognizable from the instruction example given, and am rather unable to gauge how best to edit in a way to satisfy the multi motor single axis requirements needed.  Now I am using a different board and a different configuration tool compared to author, however I would have assumed the Hal file ( 

File Attachment:

File Name: plasma_test_02.hal
File Size:3 KB
) would be somewhat recognizable? So maybe I am doing something incorrect?

If anyone has any pointers as to an any literature that might assist or in an ideal fairyland world a wizard that supports both multi motor single axis and 7I96S (and thus 2.8 master) that would be most appreciated.  
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Last edit: 10 Jun 2022 12:12 by Gruntled Raptor.

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13 Jun 2022 00:08 #245034 by andypugh
Why are you starting with a single joint if the end point is a multi-motor machine?

(And, what is mesaCT ? )

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13 Jun 2022 00:14 #245036 by tommylight


(And, what is mesaCT ? )


I was afraid to ask thinking "there is something about Mesa i do not know, shame on me"! :)

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13 Jun 2022 12:24 #245066 by Gruntled Raptor
I'm starting with a single joint as i was following the tutorial linked in the post, which relies on duplicating and edit a joint to give you two joints, 1 for each motor on a single axis. the bit i got stuck on was adding pin assignment for duplicated joint.

mesaCT is just "mesa configuration tool" which i found on the forum as natively supporting the 7I96S as the 7I96S has a different FPGA from the 7I96 this made sense as a choice for using it. i was also under the impression at the time that firmware flashing was needed on a per config bases (as this is how previous FPGA tools i worked with functioned) unfortunately i fell into the trap of previously knowing just enough (very very little) about electronics/FPGA's that i started making assumptions on how things worked and consequently got myself very very confused more so than someone coming in blind i suspect.

gnipsel.com/mesa/mesact/ -this was the config wizard i had been using and referring to as mesaCT

now that i understand that i can make ini/hal file using stepconf (cause it dosent change the firmware) which will hopefully be more recognizable when compared to the examples provided in the tutorial i was following.

this being said id still love to know how the pin assignment was being done in the hal file created by mesaCT. as i didnt see anything that specified a different pin (specifically) for the different joints (when i did a multi joint file). to be honest i dont even know which part IS assigning the pins or maybe its not pin specific and just being done as a separate headers for each set of outputs?

i mean is this where the pin mapping is being done?:

# position command and feedback
net joint-0-pos-cmd <= joint.0.motor-pos-cmd
net joint-0-pos-cmd => pid.0.command

net joint-0-pos-fb <= hm2_7i96s.0.stepgen.00.position-fb
net joint-0-pos-fb => joint.0.motor-pos-fb
net joint-0-pos-fb => pid.0.feedback

net joint.0.output <= pid.0.output
net joint.0.output => hm2_7i96s.0.stepgen.00.velocity-cmd

i think im missing some basic knowledge here that is undermining my ability to understand something that by all accounts should be fairly basic to understand.

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13 Jun 2022 15:51 #245077 by Gruntled Raptor
well using pncconfig and then changing all calls to 7i96 to 7i96s worked a treat. particularly as it had options for adding tandem axis motors.

however as i don't intend to use home/limit switches on my machines (they have all ways just been a pain for people like me who prefer to just use diligence and work piece datum's instead. i am consequently stuck by what appears to be a rather militant requirement of Linux CNC to home things before doing anything.

"cannot jog joint 1 because home_sequence is syncronised (-2)"

i understand that there is world mode and joint mode although i not sure how to switch between the two (gmoccapy) but even if i could with the error messaage seemingly ignoring the fact that "NO_FORCE_HOMING = 1" is in place i suspect id need to do something else anyway.

so is there a way to remove this "home_sequence is syncronised (-2)" requirement? i understand the risks of gantry racking but right now as i don't have any homing switches its only really getting in the way of my developing the system.

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16 Jun 2022 12:01 #245254 by Gruntled Raptor
Resolved homing issue by adding the following to INI file under each joint:

HOME_SEARCH_VEL = 0
HOME_LATCH_VEL = 0
HOME_USE_INDEX = NO
HOME_SEQUENCE = 0

This essential allows me to set HOME to current location when i click any of the home buttons for said joint/axis (exactly what I wanted) a good friend of mine went through the handbook and found these settings that worked. It seemed I got tunnel vision and was exclusively looking at the online information that catered specifically to the HAL and INI files, which meant I was completely missing out of just looking through the hand book like a more reasonable creature.
The following user(s) said Thank You: tommylight

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16 Jun 2022 12:50 #245261 by tommylight

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16 Jun 2022 15:22 #245271 by Gruntled Raptor
So I omitted HOME equals to HOME_OFFSET and nothing caught fire?

I assume this is relevant if you are setting your HOME_OFFSET to whatever value to move your "by eye home" datum to be your "cutter" datum. i.e if you had an off centre laser pointer to show your intended datum/home.

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