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Alarm Code 8 - Newbie

Discussion in 'Control Software' started by RCG3, Apr 10, 2019.

  1. RCG3

    RCG3 Well-Known
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    I just moved from TinyG to the Black Box and the Control software. Everything is connected and all axis jog in the proper direction. I have three limit switches installed and they all respond when manually triggered. When I try to Home the machine I get an alarm code 8 for the Z axis.

    Homing fail. Cycle failed to clear limit switch when pulling off. Try increasing pull-off setting or check wiring.

    The Z axis was in the middle of the range and not touching the Z limit.

    Any ideas? Sorry if this is a dumb question or already answered somewhere. I'm not very familiar with searching forums but I'm learning!

    Thanks for any help.

    Reeve
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    One of two settings:

    1. Ensure your steps per mm is setup correctly (Else in step 2 when we say "move 5mm away from the switch" and your steps are wrong, we arent going to be moving out of the switch far enough)
    and
    2. Ensure you have Grbl Settings -> Homing Pull Off ($27) set to at least 5mm. You can increase it as well (10mm) - that value tells grbl how far to "reverse" away from the switch after hitting it, to "clear" the switch (So its not making contact anymore)
     
  3. RCG3

    RCG3 Well-Known
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    Thanks for the reply. My Z axis is nowhere near the limit switch when i try to Home it. The Z moves down and the Alarm it's immediately tripped. The pull off is set to 5mm but like i said, it never hits the switch. Just moves down 5mm and trips the alarm 8.

    Thanks
    R
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If it just moves 5mm its trying to clear the switch because it sees the switch as already closed. Check the troubleshooting tab while toggling switch manually.

    Also see gnea/grbl and gnea/grbl
     
  5. RCG3

    RCG3 Well-Known
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    Troubleshooting tab shows all limit switches are "green". They are NC switches. I'm getting more confused as I go. All axis jog in the proper direction for a C-Beam Platemaker. Z homes in the wrong direction regardless of reversing or not. It did home in the right direction when I started so I don't know what's going on. I don't know if this helps but I'm definitely confused.

    [17:08:50] [ $$ ] ok

    [17:08:50] [ $I ] [VER:1.1f.20170801:CBEAM]

    [17:08:50] [ $I ] [OPT:V,15,128]

    [17:08:50] [ $I ] ok

    [17:11:57] [ update ] Checking for Updates

    [17:11:58] [ update ] You are already running OpenBuilds CONTROL 1.0.149

    [17:13:30] [ $J=G91G21Z10F5000 ] ok

    [17:14:32] [ $J=G91G21Z10F5000 ] ok

    [17:14:37] [ $J=G91G21Z-10F5000 ] ok

    [17:14:39] [ $J=G91G21Z10F5000 ] ok

    [17:15:52] [ $$ ] $0=10 ;Step pulse time, microseconds

    [17:15:52] [ $$ ] $1=255 ;Step idle delay, milliseconds

    [17:15:52] [ $$ ] $2=0 ;Step pulse invert, mask

    [17:15:52] [ $$ ] $3=6 ;Step direction invert, mask

    [17:15:52] [ $$ ] $4=1 ;Invert step enable pin, boolean

    [17:15:52] [ $$ ] $5=1 ;Invert limit pins, boolean

    [17:15:52] [ $$ ] $6=0 ;Invert probe pin, boolean

    [17:15:52] [ $$ ] $10=2 ;Status report options, mask

    [17:15:52] [ $$ ] $11=0.020 ;Junction deviation, millimeters

    [17:15:52] [ $$ ] $12=0.002 ;Arc tolerance, millimeters

    [17:15:52] [ $$ ] $13=0 ;Report in inches, boolean

    [17:15:52] [ $$ ] $20=0 ;Soft limits enable, boolean

    [17:15:52] [ $$ ] $21=1 ;Hard limits enable, boolean

    [17:15:52] [ $$ ] $22=1 ;Homing cycle enable, boolean

    [17:15:52] [ $$ ] $23=4 ;Homing direction invert, mask

    [17:15:52] [ $$ ] $24=2000.000 ;Homing locate feed rate, mm/min

    [17:15:52] [ $$ ] $25=1000.000 ;Homing search seek rate, mm/min

    [17:15:52] [ $$ ] $26=250 ;Homing switch debounce delay, milliseconds

    [17:15:52] [ $$ ] $27=5.000 ;Homing switch pull-off distance, millimeters

    [17:15:52] [ $$ ] $30=1000 ;Maximum spindle speed, RPM

    [17:15:52] [ $$ ] $31=0 ;Minimum spindle speed, RPM

    [17:15:52] [ $$ ] $32=0 ;Laser-mode enable, boolean

    [17:15:52] [ $$ ] $100=199.100 ;X-axis steps per millimeter

    [17:15:52] [ $$ ] $101=199.100 ;Y-axis steps per millimeter

    [17:15:52] [ $$ ] $102=199.100 ;Z-axis steps per millimeter

    [17:15:52] [ $$ ] $110=1000.000 ;X-axis maximum rate, mm/min

    [17:15:52] [ $$ ] $111=1000.000 ;Y-axis maximum rate, mm/min

    [17:15:52] [ $$ ] $112=1000.000 ;Z-axis maximum rate, mm/min

    [17:15:52] [ $$ ] $120=100.000 ;X-axis acceleration, mm/sec^2

    [17:15:52] [ $$ ] $121=100.000 ;Y-axis acceleration, mm/sec^2

    [17:15:52] [ $$ ] $122=100.000 ;Z-axis acceleration, mm/sec^2

    [17:15:52] [ $$ ] $130=270.000 ;X-axis maximum travel, millimeters

    [17:15:52] [ $$ ] $131=270.000 ;Y-axis maximum travel, millimeters

    [17:15:52] [ $$ ] $132=80.000 ;Z-axis maximum travel, millimeters

    [17:15:52] [ $$ ] ok

    [17:15:52] [ $I ] [VER:1.1f.20170801:CBEAM]

    [17:15:52] [ $I ] [OPT:V,15,128]

    [17:15:52] [ $I ] ok
     
  6. Award

    Award Journeyman
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    Hello Reeve,

    I'm a total newbie at this and I don't have a C-Beam (unfortunately) to test this on but I was just looking at the suggested C-Beam grbl settings here: C-Beam® Machine - Plate Maker

    Your $23 homing direction invert mask setting is different to the suggested setting. It should be $23=0 according to the documentation. Might be worth giving it a go?

    Hope this helps

    Adam
     
  7. RCG3

    RCG3 Well-Known
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    Thanks Adam. I have my limit switches installed so it homes to the front left instead of the back right. I don't think it really matters to me so I might switch them just to avoid some confusion in GRBL. I know it assumes positive direction for homing. I'm switching from a Tinyg to grbl so I'm learning grbl at the same time. I'm sure it's something simple but I'm not seeing it. I don't understand some of the options in the Control software and the explanations it offers either. Like Step Pulse Invert vs Step Direction Invert. I need a plain english explanation until I learn the lingo I guess. Another thing I'm not sure of is when they say the "pin goes high" or "low". Does that mean when the switch is closed the resistance goes low (like zero) and open means high resistance? I'm not electrical, I'm mechanical so I'm struggling a bit. Sorry for the dumb questions.
     
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  8. Alex Chambers

    Alex Chambers Master
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    Pin high = high voltage (not sure about black box but usually between 3 and 5 volt)
    Pin low = 0 volt (ground)
    If your software is expecting a high signal to indicate a limit switch is triggered a common way to do it is connecting the pin to +V with a resister ("pull up resister") and using a NC (normally closed) switch to connect it to 0V. When the switch is pressed the pull up resister PULLS the pin high.
    Alex.
     
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  9. Award

    Award Journeyman
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    I'm not electrical or mechanical and it is a continually steep learning curve for me as well :) The great thing about this forum is that there is always someone willing to help out (@Alex Chambers and @Peter Van Der Walt ) The great thing about the Workbee and xPro v3 card I purchased was that it just worked with the suggested grbl settings. The downside to that is my personal learning style is that I only really try to learn something when it goes wrong!

    The best place for a "plain english" grbl explanation is here: gnea/grbl

    Although if I am honest I have read through it quite a few times and I still don't fully get it. I've been forcing myself to reply to posts on grbl settings so it makes me learn it.

    I found an old thread on the forum which does a really good job of explaining NC and NO limit switches and the reason for putting resistors, etc. for us non electrical types.

    Limit switches / noise filtering necessary?

    Cheers

    Adam
     
  10. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    The Grbl wiki is a treasure of info: it may sound like I am not helping but do read All of it! :) reading the wiki as a whole opens up a bigger picture of how it all slots together. Even sections you dont think relates to you, like the Interfacing page, explains how it works under the hood.

    Github.com/gnea/grbl/wiki

    Theres a dedicated page on Wiring Endstops on there too (;
     
  11. RCG3

    RCG3 Well-Known
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    Well, here's some advice to any other newbies that are positive they have everything hooked up properly. Check one more time. After moving my limits to the positive direction and wiring them "normally open" I traced my wires one last time and discovered I had mistakenly swapped my X and Y limit switches. Now I have to figure out how to set the soft limits..:)
     
  12. Award

    Award Journeyman
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    Nice. Glad you found the problem.
     

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