I know that the soft limit alarm is annoying, but it works the way it was designed. We’ll start out with a list of the settings used by GRBL, note that these are settings for a Big Ox type machine with belt drive a… When you home the E3 the firmware sets soft limits for both negative and positive ends of travel for each axis. I think the initial niggle of the thread (admittedly a very minor point) is that the "soft limit error" tends to behave like a "hard limit error", whereas in reality, they are different. I tried to disabled my soft limits and the G-Code ran perfectly… Something is not right when I activate the soft limits. I try to understand which command Easel is sending ($?). Homing should be mandatory upon power-up. When correctly set up, the ‘Grbl candle home’ function will home your machine to a predefined point, this can be used if your machine is equipped with limit/home switches. Easel is good for now to understand the different steps to do before to start the carving but I feel the friendly interface gets in the way to truly understand what’s going on. X-Carve. G1 X29.12683 Y31.08368 F40.0 You cannot jog outside of the limits. It should work…I don’t understand what’s wrong…. G1 X29.12683 Y0.01693 F40.0 See here, here, and a preliminary wiki page on setting up the homing cycle, which I requested some help on here, since I don't have a lot of time at the moment. These internal settings consist of things like customizing the steps/mm of the stepper motor/driver/axis type and setting up the directions and enabling optional features. $24=50.000 (homing feed, mm/min) $20=1 (soft limits, bool) This is behavior is required. About GRBL. $112=500.000 (z max rate, mm/min) G0 X0.00000 Y0.00000 Do you want a patch to not need homing after ctrl-x ? $102=188.976 (z, step/mm) Thanks Phil. (Hard are limit switches, soft are software limits). $4=0 (step enable invert, bool) I’m trying to carve the usable area on my waste board. The $30parameter is often confusing. This covers both your suggested soft limit modes. This is slated for v1.0 development, where there will be better set behaviors for things like this. There are plenty of other resources on this topic, like at the old shapeoko wiki and numerous issues threads here. Feed rate used in the "Homing" cycle to locate the limit switches. Soft limits is a safety feature to help prevent your machine from travelling too far and beyond the limits of travel, crashing or breaking something. command. Some with bugs or others that use a different g-code dialect. More generally, I think the grbl project would be better served by "assuming" that it had an intelligent front-end pre-processor / sender that also kept state and , and then asking "what functionality should/could we reasonably migrate into the front end on the laptop/host?". A soft-limit is categorized as an Alarm, so it must stop the machine and prevent anything from being executed. 13: Safety door detected as opened and door state initiated. Already on GitHub? $122=50.000 (z accel, mm/sec^2) If these motions are still passed to Grbl, it's possible for a machine to exceed the soft-limits unintentionally. This number corresponds to the number to which GRBL will assign the code to be used to switch on the laser at maximum power. I use Easel for the interface but I use UGS to troubleshoot. privacy statement. I’m trying to carve the usable area on my waste board. This is because soft-limits performs a feed hold before throwing the alarm. (rpm min) If not, should one be added? As for whether to think about the long-term future of grbl as "only what runs on the back-end (say an Arduino)", or as a "front-end G-Code pre-processor/driver and streamer + back-end combo working together", either could work. Yes, possibly. Also Google is your friend. Also when I probe, I set the zero Z workpiece right ? g92 is a workaround and can have side effects. Feel free to test this. When playing a full gcode file, I guess this is different - it shouldn't just continue with the next command when the previous command would end up past the soft limits. When I have more access to the machine I'm working on (a day or two) I can do some more characterization and better logging of the issue. However, there is nothing wrong with having two levels of checks, where the GUI does one and Grbl still does its own. Second, a soft limit alarm does not require re-homing, even though it looks like it does. Some with bugs or others that use a different g-code dialect. I reinstalled grbl 0.9j Atmega328p 16MHZ 115200 17 04 2016 _2.hex now I can see X,Y,Z max limits, enabling soft limits etc… Tim, if I set $100=25, its moving very slowly which does not look normal to me. 12 (Compile Option) Grbl '$' setting value exceeds the maximum step rate supported. If you have limit switches, it could be noise falsely triggering them. Soft-limits are on Grbl's side for one particular and important reason. X,Y ; 740mm,790mm /29.13”,31.10” but I made my perimeter slightly smaller on purpose. When soft limits are used, doing a homing cycle after startup is mandatory. At some point, I think we can alter the soft-reset behavior for this, but GUIs can easily send a $X as well after the reset. After a soft reset, homing isn't required. Secondly, soft limits is designed to only work when homing is enabled and your machine is homed. If you are jogging, the soft limit alarm is easy to invoke, which is why in Grbl v1.1 I created the jogging command set. The homing switches and soft limits must now be enabled in the GRBL settings (GRBL is the software which runs on the microcontroller on the PCB). The Alarm2 means that the E3 thinks that the spindle has moved past one of the travel limits. G1 X0.01693 Y0.01693 F40.0 (Certainly I would kick them out if they take up space and processing cycles that could more profitably be devoted to "real grbl strengths" like acceleration, planning, cornering, etc,") And then of course, pre-processing in the host could implement all the extra things like subroutines or peck-drilling. Home GRBL controlled machine; Load g-code file into UGS and move the machine where it will hit the soft-limits when running the g-code. (And eventually this will also check for soft limit violations.) It works by knowing the maximum travel limits for each axis and where Grbl is in machine coordinates. These ignore the soft limit and just prevent the offending motion from being executed. My guess is either you went past the hard or soft limits. Today I just implemented homing and soft limits and I also found the two steps needed to clear the Alarm (Reset, then sidestep or perform homing again) a bit messy. IMO, safety protocol should be done on the motion controller and not depend on a GUI, which can be within a wide range of "plain doesn't work" to "intelligent". $100=39.900 (x, step/mm) ! @cspwcspw : I strongly disagree. There's no reason to make it more complicated. It will not throw an alarm as it would with a normal g-code command. So your problem has already been addressed and this matter is closed. $13=0 (report inches, bool) If your machine does not have limit switches, you must set parameters $21and $22to zero. If you want that code, only idle state, then i extract the patch. G-code parsers can be ever so slightly different. If these motions are still passed to Grbl, it's possible for a machine to exceed the soft-limits unintentionally. This sets the maximum travel from end to end for each axis in mm. This gives the user time to acknowledge the problem and cease streaming. It feels to me soft limits should be enforced long before the g-codes are even streamed to grbl, so I'm not convinced soft limts should even be in "core" grbl. Marlin is 3d printers, and Grbl is CNC mills and routers, which are much more dangerous than printers. $101=39.918 (y, step/mm) When a soft limit is triggered, a soft reset is required to continue. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. I'll probably replace the unshielded stepper motor wire with shielded. I have added gc_sync_position() to mc_reset in order to not needing So if I mount a small PCB on a bigger table and set some work coordinates, I don't want to go drilling outside the soft-limit bounds of the PCB. Improved jogging sounds like it would help indeed, thanks. Wait until program tries to move through the soft limits. G1 X0.01693 Y31.08368 F40.0 Running ls now should reveal the grbl.hex file that you're going to flash. Successfully merging a pull request may close this issue. Larger machines can break tools or flig metal workpieces across the room if a small error occurs. @cspwcspw : The soft limit error is not an error but an alarm. There are too many things that can go wrong that will go wrong. @chamnit the soft limit alarm very annoying whenever you power up & run homing cycle and intend to run CNC job , but the soft limit alarm appear and ask for reset to continue and when sent soft reset command the message [$H | $X to unlock ] re appeared again and should redo the last command. $111=8000.000 (y max rate, mm/min) Set this to the highest value that does not cause the machine to crash into the limit switches. Soft limits cannot be enabled without homing also enabled. After a soft reset, a homing run is again required, even though the machine position is not lost. $131=790.000 (y max travel, mm)Make XXX something larger than the machines travel. $22=1 (homing cycle, bool) $27=1.000 (homing pull-off, mm) It shouldn't matter where you limit switches are. Updating GRBL. $130=740.000 (x max travel, mm) True. Used when soft limits are enable to tell GRBL the maximum travel for each axis. This allows for a much more enjoyable and fluid GUI or joystick interaction. My G-Code moves the spindle by 29.12683" on X and 31.08368" on Y. Limits: Linuxcnc's soft and hard limits just work. again and again!!! I’m not sure at which point it detect a soft limit is reached…. G-code parsers can be ever so slightly different. $6=0 (probe pin invert, bool) It allows you to use the GRBL system with the High Torque motors to their full potential. G-code streaming is a very clean separation between the controller and a GUI. $JX or $J-X , only one axis at time and fixed feedrate. Once homed (I don’t jog it) I should have 29.134" on X and 31.10" on Y. after have issued ctrl-X $X you must issue g92 with the MPos coordinates from ? I’ve set the soft limits and tested them: work fine. G90 $132=110.000 (z max travel, mm)Make XXX something larger than the machines travel The text was updated successfully, but these errors were encountered: I understand why you want this changed, but I think what you are asking for is a better jogging interface. From the zero machine to $130, $131, $132 right? $30=1. Soft limits is a safety feature to help prevent your machine from traveling too far and beyond the limits of travel, crashing or breaking something expensive. So from now on, I home ($H) everytime. Setup Grbl Params: $20=0 (soft limits, bool) $21=1 (hard limits, bool) $22=1 (homing cycle, bool) $130=XXX (x max travel, mm) Make YYY something larger than the machines travel. G1 Z0.15000 F9.0 to your account. It'll throw a soft-limit alarm if the program exceeds machine travel without moving the machine. $26=250 (homing debounce, msec) This also requires the use of a homing cycle. Because I set $limits from the home position. Looking at things from the grbl perspective, the term "limit switch" only applies for the X-carve if you use hard limits ($21=1). I've got a scope, that's a good idea. • If soft-limits are enabled, any jog command that exceeds a soft-limit will simply return an error. $11=0.020 (junction deviation, mm) It must be in the Code…, Got it Lessons learned. thanks @chamnit I'm aware of your purpose and your comments in other issue, but honestly I've already use special version of marlin in my cnc laser but during last days I've tried to replace it with GRBL .9j & 1.1f ,and yet I couldn't find any proper setting to homing and running cnc job , it would be nice if there is forum which is successful installation shared, I really appreciated if you could create troubleshooting/ wiki page for such effort. I'm not really sure what I'm asking, I was mostly running into something and wanted to share my experience :-). Soft-limits are on Grbl's side for one particular and important reason. You don't need a lot of comm bandwidth or need to invent a new protocol, which accomplishing something very similar to g-code already. The limit switch wires and 2 of the 3 stepper motor wires are all shielded with shields connected to ground. this and not loosing the position after the stop/abort command. The limit switches are used to detect the physical limits of the working area and to position the head in initial position during the homing process. $20 - Soft limits, boolean. GRBL is a free, open-source, high-performance software for controlling the motion of machines that move, that make things, or that make things move, and will run on a straight Arduino. Hard Limits is basically the same except we use a physical switch at the end of the axis In general, you shouldn't be running into soft-limits constantly, and, if a job might come close to a soft limit, I would make sure to do a dry-run by streaming the g-code program in Grbl's check mode. Hi Guys, I need some guidance on how works the soft limits in GRBL. SiroSimo May 1, 2017, 12:56pm #1. At that point the soft limits won’t be useful as I could potentially hit something because the limits are offset by the spindle position. Soft Limits and Easel/GRBL? The home button If you have a basic machine, like a 3018 engraver that does not have limit switches, you can ignore this button and use ‘ safe position ’ instead. I might also like extra features like having soft limits on the work area rather than only on the machine limits. stops the jogging It simplifies the code management a bit. G20 (rpm max) This is only useful if you have soft limits (and homing) enabled, as this is only used by Grbl's soft limit feature to check if you have exceeded your machine limits with a motion command. 0 to -max_travel for each axis. I just don’t understand why I hit a soft limit… From my G-code, everything is under the soft limitations. To do … It should account for them. @chamnit I'm former user of Marlin firmware, I used simple task to run my CNC job, just homing and go whereas hard/soft/homing cycle enabled, is there any way to use GRBL in same easy manner (for example by enabling #define HOMING_FORCE_SET_ORIGIN )? Before you get started, there are a few things you should know about your engraver and how to set it up to get the most out of your jobs. $21=0 (hard limits, bool) $3=2 (dir port invert mask:00000010) (I don't need to redo the homing cycle). $5=1 (limit pins invert, bool) LaserGRBL will make the button disappear with the box that allows you to control homing. You signed in with another tab or window. Already in grbl, it seems that you have two loosely coupled "processes" for parsing and planning and putting things in the block buffer, then the ISR process that does the motion on the motors. $2=0 (step port invert mask:00000000) The end goal is to carve a grid so I … Perhaps there are possibilities for different decompositions: might one be better off, for example, planning the blocks and decoding the G-code before moving blocks across the USB interface to the Arduino? $110=8000.000 (x max rate, mm/min) When homed, the machine coordinates should only exist in the negative space, i.e. G1 Z0.15000 F9.0 Properly connected limit switches can significantly increase the reliability of the GRBL - the microcontroller pins connected to the … Sign in The first one would be a LB soft limit that doesn’t allow jogging going out of the travel limits because doing that, GRBL goes in alarm mode and need to be reset and you need to home again… Soft limits prevent the CNC to crash into its own frame by halting moves which would cause a crash. I realize that you can do a $X to unlock grbl after the soft reset, but that command is really something that is marked as unsafe and shouldn't be normally used. Then it's possible to continue. GRBL configuration. Adding homing switches will allow one to enable soft limits (Grbl configuration $20=1). We would like to show you a description here but the site won’t allow us. $132=100.000 (z max travel, mm). G4 P0.1, My problem is that I hit a soft limit all the time. I used easel to trace the outside perimeter of my working area. The homing isn’t a problem, it’s these soft limits that get triggered… The reset clears everything from all of the internal buffers. $10=115 (status report mask:01110011) Also below is my $$, $0=10 (step pulse, usec) $131=790.000 (y max travel, mm) Otherwise soft-limits don't work. From the Grbl Configuration guide: $130, $131, $132 – [X,Y,Z] Max travel, mm. $120=500.000 (x accel, mm/sec^2) G90 I suppose this constitutes two levels of acknowledgement, but I don't think this is much of a problem. Sure, it works as you say, and that is how I am clearing the error. $12=0.002 (arc tolerance, mm) To prevent exceeding max travel DURING a job. Most open-source 3D printers have Grbl in their hearts. I thought about decoupling Grbl a while back and decided against it. I set my soft limits from the front left corner (my homing position, seems to be the standard for a lot of people) so they are all positives. It’s what I’ve done then but still have these soft limits triggered. but it works only in idle state. G0 X29.12683 Y31.08368 We’ll occasionally send you account related emails. G1 Z-0.06250 F9.0 @cri-s : Grbl checks all motion commands, except homing, if the commanded motion exceeds the machine travel limits. I need some guidance on how works the soft limits in GRBL. That is the purpose of $X. If I restart the machine and $X, I understand that it’s going to set the zero machine right where is the spindle. If the maker movement was an industry, Grbl would be the industry standard. $25=750.000 (homing seek, mm/min) These are treated and should be treated differently. But I think I agree with Chamnit's point of view: the GUI can easily cope with the two steps if it needs to. By clicking “Sign up for GitHub”, you agree to our terms of service and I suspect the Z axis…, Powered by Discourse, best viewed with JavaScript enabled. I mostly ran into this while jogging manually, where I'd like the soft limits to prevent me from jogging too far, but then continue to respond to subsequent jogging commands. Setup Arduino UNO, CNC Shield v3, GRBL, and related CNC motion components and electronics. Resuming after soft limit without homing cycle. Just unlock the Alarm and you can resume operation like normal. If I have not set a feedrate on a G1, for example, I get an error, but not one that requires two steps to clear. Homing switches allow soft limits ($20=1) to work. $1=255 (step idle delay, msec) The end goal is to carve a grid so I can have an exact square referential to clamp pieces. Are your homing switches wired Normally Open or Normally Closed? For Jogging, if only in idle state, it's simple. The unshielded stepper motor wire is not next to the x-axis limit switch wire (that's the one with the problem). How to Make GRBL + CNC V3 Shield Based Mini CNC Machine From Scrap DVD Drive: This CNC is based on GRBL0.9 Firmware and CNC V3 shield GRBL is Hacked for Z-axis Servo.CNC Shield & GRBL combinly works very preciselyIt is loaded with very useful functions like Hard limit, Soft limit, Homing, etcThis is about how to make GRBL… command is So even if your soft limits are off, make … $23=3 (homing dir invert mask:00000011) Bob and Keith talk about the importance of the homing the E3/E4 CNC Router. change Grbl's states and running modes, and start a homing cycle. Like you stated, it's just not elegant. 11: Max characters per line exceeded. $121=500.000 (y accel, mm/sec^2) @mkeyno : There already is. $31=0. Troubleshooting. Ultimately I think I’ll switch all the time to UGS. They are wired Normally Closed and I’ve an noise insulation with opto-isolators. Now that we have GRBL up and running, it’s time to get the settings for GRBL lined up with our machine. The Alarm2 means there has been a g-code command or a jog move that is asking to go past one of these limits. Is there any other way to more elegantly deal with soft limits? GRBL has a list of internal variables which must be customized for the machinery connected to the controller. You may have better luck at a GRBL forum. I troubleshoot this part few weeks ago and it works all good now. This is for two purposes. Once all the paths and configurations are set, run make clean make in the top-level directory of the GRBL version you cloned (a folder named grbl-1.1f.20170801 or something like that ). Looking at things from the grbl perspective, all other cases for the X-carve the switches are "homing switches". When toggled off, Grbl will perform an automatic soft-reset (^X). Line was not processed and executed. Here is the Gcode associated: G20 And if you execute a command in MDI that attempts to go outside of the limits you get errors, but you have not lost steps that require you to re-home.