Grbl limit switch noise

 

This is due to how the 328p chips pin change interrupts work. In this video, I discuss how to wire the switches, h Dec 27, 2019 · Hence why you get links to gnea/grbl. From the Docs: "By default, the limit pins are held normally-high with the Arduino's internal pull-up resistor. I have connected them as normally closed in serial. Apr 8, 2020 · I am running GRBL V1. There are internal pull-up resistors in all of the limit pins. This will increase the distance the axes will move off the switches after homing. 9j. Feb 14, 2021 · Preamble. This way you pull the signal low, and push the signal high when triggered. As far as limit switches are concerned the best solution by far is just to make them normally closed. Have you set your travel distances with $130, $131, $132? Apr 16, 2021 · That kind of short would be pretty rare. Jan 15, 2021 · That kind of short would be pretty rare. I really like the blue solder mask, it looks great with the blue LEDs, blue connectors and blue Mar 8, 2013 · The limit pins detect a pin change, not specifically high to low. (I tried all combinations of connecting them serial or parallel and reversing or leaving alone the limit pins (in the GRBL settings, around $15)). If I disable hard limits, jogging works. Values of 3K ohms and 0. 1 Limit & home switch Guidehttps://github. One place to start for the desktop CNC is the gnea/grbl wiki: Wiring Limit Switches. If Grbl is alarming out, it can be two things. ” Apr 16, 2021 · Grbl refuses to start any move that will exceed the soft limit. There is a lot of literature about homing and limit switches. Experiencing alarms with no switches connected Nov 2, 2014 · 56. Jan 15, 2021 · In my case, the noise on my switch lines manifested as the NO switches I was using showing as tripped when they weren’t, which is the opposite of what you’re seeing. Make sure to look for the version of grbl you are using. 1" pitch) and conect my limit switches to that. As Peter says above, OB limit switches are NO. Aug 21, 2020 · ttraband (Tom Traband) August 21, 2020, 10:29pm 28. One thing I didn't realize if you get that specific board is there's only one x,y, and z. 1, the 3018-PROVer V2 elevates performance with silent Toshiba TB6S109 drivers sporting 32 Download it as . For the opposite behavior, just invert the limit pins by typing $5=1. Cc: gentlejim rbjg@xtra. Built on the foundation of open-source Grbl v1. 1. com. 1f. See the Wiki for details. Unveiling unparalleled value, the V2 delivers an even smoother setup in under 20 minutes. In this case, make sure your homing pull-off distance Apr 15, 2020 · I use grbl 1. The eStop pin on the CNC shield is wired to the restart button of the Arduino. I had everything set up on my cnc laser engraver, all wires run through the cable chain and plugged in to my arduino with a shield. Navigate to the extracted folder “grbl-master”, in there select the “grbl” folder and click the open file. Usually when powering on/off router and / or dust collector. Each Stepper Motor Driver needs to be connected to the following pins: Limit Switches prevent the machine for over extending each axis and are connected to Pins 9-11. Optoisolated Limit Switch Isolator for CNC Machines. 9. It will hit the limit switch back off a bit, re hit the switch slowly, then back off the amount in $27. There are plenty of resources on various limit switch wiring. A 1uF capacitor will be polarized so connect the negative pin to ground. perfectly interpreted by the 0. Sorry it didn’t resolve the noise problem in the endstop wiring. Aug 27, 2020 · Nor will $24-27. On my grbl board I soldered a screw terminal block (0. Jul 17, 2013 · Thank you all for all your help Cheers Jim. The Z axis did not go down/move at all thus the message of Homing Failed. I assumed it was line noise at first. Wiring only requires a normally-open switch connected to ground. . dart1280 (Mike) April 17, 2021, 8:20pm 57. If you have noise in the end stop wiring, $21=1 is going to continually put the machine in an alarm state. To enable it, you should uncomment the line 206 in ccpu_map. If the maker movement was an industry, Grbl would be the industry standard. Here is a link to the limit switch portion. I have plan to run limit switches in NC mode. It started with Z, and now the X moved but just until the Y hit the limit switch and It gave the same Alarm:1. I am using grbl 0. )" Optical switches any relays are a great idea. It doesn’t stop a current move when the machine gets close to the limit, it prevents the machine from starting a move that it predicts will cross the limit. $23 - Homing dir invert, mask. It discusses all these things and will save a lot of time and confusion for people new to using GRBL based CNC machines. co. Is it always necessary to install the 4,7K resistor and 100nF capacitors or just in case of noise problems. Thanks again. ZIP file and then follow these steps: Open the grbl-master. The status report shows the state at the instant that it is given. Apr 15, 2021 · Grbl refuses to start any move that will exceed the soft limit. 5x the max travel distance. You will need to add noise filtering and shielding to your limit switches. The NPN transistors on board are used to invert the signal from the photocouplers and light an LED every time a limit switch is triggered. ” There are some tasks Genmitsu 3018-PROVer V2 Upgraded Desktop CNC Router Machine with GRBL Offline Control, Limit Switches & Emergency-Stop, XYZ Effective Working Area 284 x 180 x 40mm (11. Im Sorry to be so vague but im on mobile and busy. May 9, 2023 · N_AXIS is defined (like axis names) at compile time in the file config. Ill try to explain more later. Jul 16, 2022 · In my experience noise like this is often the result of: Poor grounding designs that daisy chain power and ground signals and the associated grounds associated with the sensors. It's also possible for motor noise to get in through the power supply. They use on-switch RC filtering to eliminate the noise (the filtration should technically be as close to the Arduino pin as possible, but maybe Peter added some more capacitors in there as well? Probably doesn't make too much difference on most small machines). Mar 2, 2017 · I tried to set $23 to 1. I don’t think you want your endstops resetting the microprocessor. Grbl defines the home position at one of the extreme corners of your machine. Your drawing shows daisy chained grounding on the switches. Apr 4, 2017 · Hi, I'm running my CNC using GRBL on an Arduino Uno. Two, your work coordinate system offset are not on the origin and your commands are Jan 10, 2022 · @dart1280 is correct. I have been looking at the descriptions of the grbl settings to figure there meanings and came across $21 & $22. I just picked up several Xtension limit switches to replace some damaged micro switches. 2 x 7. May 26, 2020 · This board is a simple circuit with three optocouplers (LTV-817 or equivalent) to isolate six limit switches (2 per axis of my CNC machine) and the noise that is generated on the lines. Most open source 3D printers have Grbl in their hearts. I have read everything about limit switches and decided to build a pcb with optocouplers. Nov 30, 2015 · X-Carve Troubleshooting. h. In the NO case, when the switch is in its untriggered state (open), it does not conduct electricity. The pullups in the Arduino are the internal ones which are about 50K ohms, this is just a vague suggestion of a pullup and is very susceptible to noise. I will say it again - You do not need endstops at all in order to use the machine. tl;dr = If you experience noise on the limit switch (or false triggers), wire your limit switches as NC to ground, set $5=1. 90% of the time, in order for grbl to be able to tell the switches apart, they need to be wired to different pins. If a limit is triggered between status reports, but is untriggered before the next one it will throw the alarm, but not show on the next status report. May 19, 2021 · The axis should move towards the limit switch, touch it, back off and repeat at a slower speed. Then you would need to enable homing and limits within grbl. The normal limit switch scheme for grbl is that the inputs are connected to 5V through a high value resistor inside the chip on the Arduino, this is know as “pull up”. $26 - Homing debounce, ms Whenever a switch triggers, some of them can have electrical/mechanical noise that actually 'bounce' the signal high and low for a few milliseconds before settling in. 1 x 1. The max travel distance is controlled by $130, (for x), $131 (for y) and $132 (for z). This guide will be applicable to other diode lasers (such as an AtomStack), especially those May 17, 2014 · @Scott216 I don't use a seperate powersource for my switches since: "Limit pins are held normal high with internal pull-up resistors. One of the first things to note is the Woodpecker board is designed such the Aug 19, 2020 · If the machine is still giving you un-commanded alarms then, as Tom says, you have a noise problem, separate all the data lines from the power lines and fit suppression caps to the limit switch wiring as Tom suggests, If you only get the false triggering of the limit switch when the trimmer motor is running you may have an electrically noisy Jul 12, 2015 · Thanks. 9 and beyond. Apr 18, 2021 · Uff. The switches are connected such that they are normally open and the logic in the Arduino will see a value of 1 as the pins are “pulled up”. There are four small adjusters for ‘current’ on the Monport Controller next to the stepper motor drivers. $26 - Homing debounce, milliseconds Whenever a switch triggers, some of them can have electrical/mechanical noise that actually 'bounce' the signal high and low for a few milliseconds before settling in. Small “104” ceramic capacitors slipped into the connectors at the control board end solved my noise problem. To: grbl/grbl grbl@noreply. These are the hard limit switches and homing function. When running a CNC job, the job itself uses “work coordinates. All of your cables for the limit switches act as antenna and send this noise back to the pins on the Arduino. A quintessential entry-level CNC, perfect for skill acquisition, artistry, DIY gifting, or launching a micro-business. 8c firmware on Arduino UNO and now everything works correctly. Try a 0. $26 – Homing debounce, milliseconds Whenever a switch triggers, some of them can have electrical/mechanical noise that actually ‘bounce’ the signal high and low for a few milliseconds before Aug 20, 2020 · If the machine is still giving you un-commanded alarms then, as Tom says, you have a noise problem, separate all the data lines from the power lines and fit suppression caps to the limit switch wiring as Tom suggests, If you only get the false triggering of the limit switch when the trimmer motor is running you may have an electrically noisy Jan 18, 2016 · The simplest wiring is limit pin to switch to ground for both NC and NO switches. GRBL can't distinguish min from max, you have to configure it to know if the switches, used for homing, are at min or max travel ($23) and are NO or NC ($5). Posted by Bill on 28th Dec 2018. It tries to move when I push the initialize Jul 3, 2016 · ErikJenkins July 3, 2016, 3:25pm 2. zip file and extract the files. Leave $21=0 and you should be able to run the machine with no problems. 1 microfarad yield an upper cutoff frequency of 500 Hz. Jul 1, 2023 · This should show the current status of your limit switches. 00 silkscreen shows min and max end stop connections, the min and max pins on a given axis are in parallel. Second, if the homing cycle doesn't disengage the limit switch when trying to pull off them. It then provides schematics, board layout files, and assembly instructions for an optocoupler-based limit switch breakout board to filter noise and protect the controller. Homing will set the machine space as 0,0,0 or in all negative space in the edge version and going forward. This is an easy to use limit switch optoisolator board. My advice to everyone when using GRBL based controllers is to thoroughly read the GRBL wiki and refer to it often. ZIP Library…. com/gnea/grbl/wiki/Wiring-Limit-SwitchesGrbl Arduino CNC Wiring Limit Switcheshe limit s Oct 30, 2019 · 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. When a limit pin is low, Grbl interprets this as triggered. Have you set your travel distances with $130, $131, $132? It offers noise reduction and galvanic isolation between the limit switches and the mirocontroller. com Aug 23, 2020 · Sorry it didn’t resolve the noise problem in the endstop wiring. Jun 2, 2013 · Grbl detects a change in the pin state, not just high or low. 1. Sent: Saturday, 20 July 2013 7:29 AM. Jun 14, 2021 · I opened my shop and turned everything on, I hit initialize, the Z axis went up and as it as it started moving along the X axis toward home it moved but made a loud BURRRRR sound and when it got to home it stopped and froze making the loud BURRRR sound for 8-10 seconds or so. The main reason for doing this is electrical noise from the stepper motors and from the router motor can cause the limit switch inputs to trigger. I would suggest just building it straight and if you have trouble with noise, then add a capacitor or a smaller pullup resistor. 6 inches) - Amazon. One hard limit is enabled and you have some electric noise problem triggering the limit pins. 1,646. Apr 2, 2016 · First, when Grbl doesn't find the limit switch within a search distance. An IO pin can only be used once. Issue the command $$, in easel I think it is in the machine inspector area. By default, Grbl assumes your homing limit switches are in the positive direction, first moving the z-axis positive, then the x-y axes positive before trying to precisely locate machine zero by going back and forth slowly around the switch. It means Grbl_ESP32 detected an activated switch before homing and tried unsuccessfully to clear the switch by backing off. Aug 28, 2020 · Glad to hear your wiring is sorted out. Also make sure your that the z-limit is on pin 12,not pin 11, if you are using variable spindle (enabled by default since v0. As for helping eliminate line noise, I've heard that shielded cables work well. These numbers are also used for soft-limits, and should be set slightly below Dec 20, 2023 · Adjust to whatever rate gets to the limit switches in a short enough time without crashing into your limit switches if they come in too fast. For the 330 resistors, I just soldered them to the underside of my Arduino Uno. By default, when the grbl controller starts up it begins in an alarm state. From: samitray notifications@github. 8c version of grbl, I reloaded the 0. Sep 14, 2016 · You need to make $21=1, $22=1, $26= 250, $27=5. If/when you want to use the board to control the spindle, you’ll plug those wires into the Z limit switch connection. While the CNC Shield v3. Thanks @dart1280. " The document discusses wiring limit switches for GRBL controllers. I am using UGS version 2. As soon as I trigger any of the switches I get an alarm. 9x versions, the D9 (X) D10 (Y) D12 (Z) pins are assigned to the limit switches, while the cnc shield uses the D9 (X) D10 (Y) D11 (Z) pins. I home to Z max and use a separate probe pin (enabled in the firmware Limit and homing will be tied to the same pin, FYI. 9). Description. I am using a CNC shield 3. 9j or later installed on your Arduino. github. 539 $1=25 17:57:47. Grbl is smart enough to know which direction was it was moving and uses that to infer whether min or max was tripped. I also have a 0. LarryD August 14, 2018, 1:23am 3. I have a CNC machine running grbl and I have 6 limit switches. Nov 8, 2019 · This video is about Grbl 1. This development is based on the use of the RAMPS expansion card which offers 2 limit switch connections per axis, a minimum limit and another maximum. Mar 26, 2019 · I made this very shaky video to help a Facebook friend set up the limit switches on his DIY CNC machine. In the 0. Mar 3, 2018 · On the GRBL Web site it Says. Have you set your travel distances with $130, $131, $132? Aug 31, 2020 · ttraband (Tom Traband) August 19, 2021, 2:14pm 61. I use a DC to DC isolation converter on board to isolate the 5V rail on the limit switches but the ground is common with the arduino. Apr 17, 2021 · That kind of short would be pretty rare. Maybe I’m really overbuilding it. But that is not for homing, just for limit switches. Apr 16, 2021 · That kind of short would be pretty rare. The main advantage is the default Grbl config is for NO switches, you need to first change $5-setting for NC switches. $21=1 hard limits is on. 539 $2=0 Sep 16, 2021 · About Grbl. What you are likely seeing is electromagnetic interference, which can be caused by your limit pin wires being too close to your stepper motor wiring, a power supply, or even a fan. Below the layout of the pins on the Arduino board. A lower value resistor (1K) may also help (with or without the capacitor). This enables reliable, consistent alignment within the engraving or cutting area with less work for the operator. You’ll need a volt meter and you’ll need to know more about the stepper motors if that’s the next step. It doesn't matter which one, but you will need to set it up correctly with the homing mask. ) So if it's switches off after homing, you'll trigger a hard limit. Oct 12, 2020 · This is a continuation of my prior blog on limit switch mounting hardware design for the CNC3018. I still get random triggers from the limit switches. The optical isolators on the board filter out the noise from the longer cable runs that go to the switches. I think cnc currently has them set as 0 which is disabled. I changed my limit switches cables for shielded ones, rerouted limit cables away from the stepper and spindle cables. If you’re using NC switches, you need to tell grbl that by setting $5=1. Brushed spindles are very "noisy" EMI wise. Optical isolation of the switches back at the board prevents this - even if you are still only switching at 5v Feb 15, 2023 · Add a Low Pass Noise Filter. As with most information on the internet: some is good, some not so good. Did you put any pull up resistor? Filtering capacitor? Maybe there is some noise from stepper then trigger your switch pin. nz. The homing cycle is $22. GRBL will give up searching for a limit switch after 1. You can modify this by recompiling the firmware, but you can also just start each session by “unlocking” the machine. The software does not differentiate between the min and max limits and An open source, embedded, high performance g-code-parser and CNC milling controller written in optimized C that will run on a straight Arduino - Wiring Limit Switches · gnea/grbl Wiki May 25, 2021 · Grbl refuses to start any move that will exceed the soft limit. 0 and I aware that grbl changed the pin out from 0. In cncjs there’s an “Unlock” button for this at the top right of the screen. I thought there's a short between the X and Y limit switch. h: #define ENABLE_RAMPS_HW_LIMITS. I have Hard Limits and Soft Limits disabled ($20=0 and $21=0) I have triple checked and they are set to 0. Jan 1, 2020 · I am running into a problem where I get an ALARM:1 when when I try to jog the machine. By default, the hardware limits are not enabled at compile time for performances reasons (checking hardware limits use few CUP cycles for each movement). Jogging also works in the Setup Wizard, as do the limit switches. Experiencing alarms with no switches connected and $5=0 set May 7, 2018 · With NO switch $5=0 should be ok because of internal pull-up keeps pin value high unless you close the circuit to the ground with switch. May 4, 2016 · Grbl is an opensource software that turns your Arduino development board into a full blown G-Code interpreter. ". But the Z at the top doesn't work. Grbl z limit switch not working. First try to increase the "homing pull-off" parameter. It describes normally open and normally closed switch connections and recommends adding pull up resistors, capacitors, or optocouplers to reduce noise. Although, if you have severe limit switch line noise, you may run into a problem with homing not working correctly. If it just does a short slow move and issues an ALARM 8. Wiring Limit Switches · gnea/grbl Wiki · GitHub. 0, $24= your machine's safe speed. I have 5 working. Low pass noise filters: These will primarily be of use on limit switches and other connections that don’t need to respond blindingly quickly. Apr 13, 2016 · Peter Van Der Walt OpenBuilds Team. When you test the home cycle, take out your router, if working correctly, the machine will rise to the Z limit first, then the Y limit and then the X limit. I've tried Unlock and $0 which work if I have not triggered a limit switch. A simple resistor and capacitor may be used to create the filter. (This is for multiple reasons that you may or may not care about. There are 3 photocouplers (one for each axis) and a 5V to 5V isolation module. I also read that it’s good to run them on higher voltage than arduino is running. I do not have any limit switches and they are diabled in the program. Grbl Setting Adjustments for Limit Switches and Z Probe. I measure the X(pin 9) and pressed the Y limit switch but it was all time high. May 17, 2014 · @Scott216 I don't use a seperate powersource for my switches since: "Limit pins are held normal high with internal pull-up resistors. I just used the machine a few days ago and Jan 29, 2024 · Grbl has detected your limit switch as triggered due the noise and skipped to the pull-off motion phase of the homing cycle. Each axis only gets one limit pin on the Arduino Uno. The control board has no way to know how many switches are attached, it it only knows whether it is receiving a signal on a pin or not. Jan 7, 2022 · Hi All, I just received my Nomad 3 and followed the tutorial, removed it from the box, cut the zip ties, plugged it all in, downloaded and installed the software. 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. Dec 28, 2018 · Limit Switches – a better way. So, if you have 2 switches wired in parallel to the input Oct 21, 2017 · It still could be a limit switch trigger. Aug 23, 2017 · I have had a lot of phantom limit switch triggers with GRBL and Arduino boards, especially the Arduino Nano. The problem is that while the machine is running it keeps freezing and the Console in CNCJS says that it was a Hard Limit activated. May 25, 2017 · Today I installed limit switches across the whole CNC router, the switches worked, for sure, I tested them with a multiemeter after the whole process on the end that goes to the Arduino board. Mar 21, 2017 · In the meantime I am busy to draw the electrical drawings, see attachment. To use NC, you need to wire the switches in series. Adjust to whatever rate gets to the limit switches in a short enough time without crashing into your limit switches if they come in too fast. That’s also why opto comes in the game. 2 and Arduino Uno R3 with Grbl 0. ErikJenkins July 3, 2016, 3:26pm 3. I would run a twisted pair from each switch to the Arduino and connect all the signal grounds to a single The setup of the limit switches in FluidNC is very flexible. Have you set your travel distances with $130, $131, $132? Aug 19, 2021 · Grbl refuses to start any move that will exceed the soft limit. ” Limit switches establish “machine coordinates. If you are having difficulties with your homing switches you can do a quick test with Grbl to see what the state of the homing switches is from Grbl’s point of view. Sometimes I'm having problem with false alarm from my limit switchs. So make sure you have your max travel settings roughly correct. This guide shows the steps to install limit switches on a Sculpfun S9 diode laser using off the shelf components, and some laser cut parts. Open the Arduino IDE, navigate to Sketch > Include Library > Add . Homing travel. Xtension Switches have onboard RC noise filtering, so no real need for normally closed. This doesn't stop you using both min and max switches; after homing, all GRBL knows or cares about is "limit triggered => stop". May 27, 2014 · I use a 330 ohm pullup resistor between +5v and the limit limit switch input. It could be noise that is triggering the limit which could be of such a short Jul 28, 2014 · Otherwise, pretty much all you need to do is enable soft limits feature and ensure your z max travel is set to 200mm. Sep 10, 2016 · My limit switches seem to be extremely sensitive to electrical noise. That indicates a limit event has occurred. See the limit switch wiki page for more information. On the internet I saw several posts that saying that the NO limit switches on the X, Y, Z axis can bring noise problems. ” So I have a brand new nomad and haven’t seen it move yet. The only way I can reset the alarm is to exit the wizard and cycle the arduino communication. When triggered, it closes and conducts electricity. the value for. This distance is about 1. LarryM November 30, 2015, 12:49am 1. 2 for each axis. This is an easy to use CNC optical limit switch isolator board for GRBL or any other control systems. 1uF cap between ground and the limit switch input. Opened up CM and tried to initialize the machine and I get the “GRBL Error: Homing Failed, couldn’t find limit switch. Nov 2, 2023 · The answer depends on the kind of switch - normally open (NO) or normally closed (NC). It supports basic axes as well as ganged axes with or without squaring. Jan 3, 2020 · edited. PCBWay made these boards for me with excellent results. *bonus points – wire signal to common, NC to ground, and NO to 5V. Oct 13, 2021 · This phase is all about accurately finding the trigger point for the limit switch. $21=0 hard limits is off. Because the optoisolator provides no direct connection between the switch and controller, noise introduced into the cables will not Aug 14, 2018 · DVDdoug August 14, 2018, 12:46am 2. I have and will read this post several times. Subject: Re: [grbl] Limits & Homing on Arduino Mega 2560 running GRBL ( #253) @gentlejim I think you may also need to change the limit pin numbers on Aug 19, 2020 · If you’re using NC switches, you need to issue a $5=1 command. $5=1 should be correct for a NC switch wired to GND. Aug 19, 2020 · Attach the Z limit switch to the white SpnEn and the black ground right next to it. Google "grbl pinout" and look for the limit switches pins. This allows it to be both feature rich and allows for very low input pin count. 539 $0=10 17:57:47. Yes, the homing cycle still works with hard limits disabled. I am using UGS and can get as far as clearing the boot alarm and running the homing sequence without issue. This can cause false triggering. If you have issued the $5=1 command, disconnecting your NC switches will interpret them as being tripped, so you might want to try a $5=0 with nothing connected to see if you still get alarms. It provides an easy way to limit noise from getting into your GRBLDuino or other CNC controller. What did I wrong? 17:57:47. (For both ends of an axis, simply wire two in parallel into the same pin. NOTE: In order to use this procedure you need to have grbl Version 0. @jeffeb3 you are right. May 7, 2015 · I'm making a PCB for my Shapeoko desktop CNC machine in order to isolate the Arduino Uno from noise on the limit switch wires and pushbutton wires. That’s excellent writing. 5 times the max travel of the axis. 1uF or 1uF capacitor in parallel with the resistor. By default, grbl is expecting NO switches, so will interpret an NC switch as being tripped. grbl-Mega-5X is an evolution of the original grlbl program which has only one limit switch connection per axis. Sonny Jeon said: ↑. Because the optoisolator provides no direct connection between the switch and controller, noise introduced into the cables will not Aug 20, 2020 · By default, grbl is expecting NO switches, so will interpret an NC switch as being tripped. Sep 24, 2020 · Adjust to whatever rate gets to the limit switches in a short enough time without crashing into your limit switches if they come in too fast. Properly connected limit switches can increase significantly the reliability of the GRBL - the microcontroller pins connected to the switches are very vulnerable to any noise. Because the optoisolator provides no direct connection between the switch and controller, noise introduced into the cables will not propagate to Basically you put the optical isolator close to the control board so there aren't long runs of wire there for noise to be picked up. Some keys are under the homing: group for the axis and some are under the motor<0 or 1>: group. dr zl wo jg lu ls cz qh aa tm