FAQ: Linkbot Troubleshooting

How do I calibrate my Linkbot's motors?


Linkbots come pre-calibrated from the factory, but after use for awhile they may sometimes need recalibration. To recalibrate the motors, follow these steps:

(1) Notice that there are eight small notches around the edge of each black hub on a Linkbot. One of them is marked in white. Position each joint of the Linkbot to its zero position by moving the white notch so that it lines up with the notch at the top of the housing, as shown in Figure 1 below. (The Linkbot may be on or off as you position the joints. But if it is on, and If the robot is currently actuating any of its joints, or if the joints feel stiff and immovable, power the robot off and on again, or while it is on press both the A and B buttons simultaneously to relax the joints. If the joints are already relaxed, then pressing the A and B buttons at the same time will stiffen them. Putting a snap connector on the hub will also aid in turning it.)

Figure 1: Lining up the white notch in the zero position for one of the Linkbot's hubs.

(2) With the Linkbot powered on, push and hold the A and B buttons at the same time until the motors begin to move. The hubs will move for about 5 seconds as the robot recalibrates itself.

(3) Once the hubs have stopped moving, they should have returned the notch on each hub to the original zero position. The Linkbot is now recalibrated and should run more smoothly.




Anytime we run a program the Linkbot moves but it glitches out by turning and jittering as it moves. How do we fix this?


Please see the answer above for "How do I calibrate my Linkbot's motors?"




My robot's motors seem jerky when trying to move at a constant velocity. How do I fix this?


Please see the answer above for "How do I calibrate my Linkbot's motors?"




My robot's zero position is off. How do I recalibrate it?


Please see the answer above for "How do I calibrate my Linkbot's motors?"




How do I update my Linkbot's firmware?


PLEASE NOTE: If you are using MacOSX 10.13 or 10.14, there is a known bug whereby the firmware updating process stalls out. Until the bug is fixed, one way to get around the problem is to connect the Linkbot or dongle that needs updating to a Mac running OSX 10.10, 10.11, or 10.12, or a Windows machine or Chromebook, and follow the instructions below to update the Linkbot or dongle firmware. Once the firmware is updated, the Linkbot or dongle should work fine with MacOSX 10.13 and 10.14.

Instructions to update firmware:

Before you start, please note that the Linkbot that is having the firmware updated needs to be connected to the computer directly through the USB cable, not through a wireless dongle. In addition, you cannot have both the Linkbot and a dongle connected to the computer at the same time (that is, one connected to one USB port and other connected to a second USB port). Similarly, if you are updating the firmware on a dongle, don't have a Linkbot connected too.

If you are using a PC, Mac, or Raspberry Pi (instructions for Chromebooks follow below):

(1) The first step depends on whether you are using the Linkbot Labs application directly or accessing it from within RoboBlockly. If you are using it directly, then click on the white “gear” icon at the top right of the Linkbot Labs window (circled in red in Figure 1 below).

Figure 1: Linkbot Labs user interface with the white “gear” icon circled.

If instead you are accessing Linkbot Labs using RoboBlockly (whether online at roboblockly.org or via C-STEM Studio), open the Linkbot Labs sidebar on the left side of RoboBlockly by clicking on the “Linkbot Labs” arrow that is directly underneath the RoboBlockly heading (circled in red in Figure 2 below). Then click on the black “gear” icon at the top right of the Linkbot Labs sidebar (circled in red in Figure 3 below).

Figure 2: RoboBlockly user interface with the Linkbot Labs sidebar closed. Click on the “Linkbot Labs” arrow, as circled in red in the image, to open the sidebar (or close the sidebar, if open).

Figure 3. RoboBlockly user interface with the Linkbot Labs sidebar open. “Gear” icon is circled in red.

(2) A “Help” window like that shown below in Figure 4 should appear.

Figure 4: Help window for Linkbot Labs.

(3) Click on the link titled “Start Linkbot Firmware Updater” and a window similar to that shown in Figure 5 below should appear. Follow the instructions listed.

Figure 5: Linkbot Firmware Updater window.

(4) Tip: If the firmware updating does not start (as indicated by the progress bar and % sign at the bottom of the window), repeat the indicated steps. Occasionally it takes several tries.

If you are using a Chromebook:

(1) Launch the "Linkbot IDE" extension, if not already open. (If you're not sure, or can't find it, go to www.barobo.com/downloads and click the "Linkbot IDE" button in the Chromebook section.)

(2) The Linkbot IDE window will appear, as shown in Figure 6. Click the "Firmware Updater" button.

Figure 6: Linkbot Firmware Updater for Chromebooks.

(3) A page like that shown in Figure 7 below should appear. Follow the instructions.

Figure 7: Linkbot Firmware Updater app instructions for Chromebooks.




What do I do when Linkbot Labs does not recognize my robot, or I get a connection error such as "localhost refused to connect"?


  • Make sure the Linkbot is turned on. Turn it on by holding down the power button until the purple LED turns blue. Note that plugging it in does not automatically power it on.
  • Make sure the Linkbot is properly plugged into your computer via the USB cable. If the Linkbot is connected to the computer via the wireless dongle, try using the cable to connect it directly to the computer.
  • Make sure the LinkbotLabs service is running. To restart the service, right-click on the “L” in the Windows task list at the bottom right of the screen (Figures 1 and 2 below) or click on the “L” in the Mac menu bar at the top of the screen (in the list of icons on the right side of the menu bar, Figure 3 below). Choose “Restart Linkbot Service” from the popup menu. If the "L" is missing, restarting the computer should solve the problem, as the Linkbot Service is launched automatically when the computer starts. If you are using a Windows machine, an alternative to restarting is to double click the "LinkbotServiceManager.exe" program located at C:/Program Files (x86)/LinkbotLabs 2.1.x.
  • The problem may be a faulty USB cable. Try connecting the Linkbot to the computer with a different cable.
Figure 1: Accessing the Linkbot Service “L” in the Windows task list. Figure 2: The popup menu with Linkbot Service options (Windows interface).

Figure 3: The Linkbot Service “L” in the Mac menu bar (your list of icons will be different). A similar popup window as for Windows (Figure 2) will appear when you click the L.




I exhausted all the options for connecting a Linkbot with Linkbot Labs or a Ch program. What else can I do?


Try unplugging and replugging your Linkbot or Linkbot dongle from the computer, restarting Linkbot Labs, turning your Linkbot off and on again, or substituting a different USB cable (in case the cable is defective). If those things don’t work, try updating the firmware of the Linkbot (see question above on “How do I update my Linkbot’s firmware?”).




When I open Linkbot Labs in C-STEM Studio it tells me I’m in offline mode even though I am connected to the Internet. What should I do?


Your Internet filtering settings may be blocking linkbotlabs.com. Add linkbotlabs.com to the list of approved sites and try again.




I'm using Python to control my robot and getting a "Runtime Error: NO_ROBOT_ENDPOINT" message. What does this mean?


This usually means that a functioning Linkbot or dongle was not detected. Make sure you have at least one Linkbot (or dongle) physically attached to your computer with a good USB cable.




I'm using Python to control my robot and getting a "Runtime Error: Connection time out" message. What does this mean?


This usually means that a robot with the requested Serial ID could not be found. Make sure that the ID is typed in correctly in your program, and that the remote robot is powered on. If you are trying to connect wirelessly to a robot in an environment with lots of RF interference (for example, in a room with many Linkbots, cell phones, etc.), it may take several tries to connect to your Linkbot.




I cannot update the firmware--what do I do?


Things to check that might be the problem: A Linkbot or wireless dongle to be updated with new firmware must be connected to the computer through a USB cable directly. If you have a Linkbot and a wireless dongle both connected to the same computer using two different cables, you will not be able to updae the firmware (i.e., make sure just one is connected). If both Linkbot Labs v1.x and 2.x are running at the same time, you will not be able to update firmware. In Windows, you can find out if Linkbot Labs v1.x is running and uninstall it. Launch "Task Manager" by the combination of the keys Ctrl-Delete and click the "Services" tab. Linkbot Labs v1.x is still running If a service named "baromeshd" is in the list. You will need to uninstall Linkbot Labs v1.x using the Control Panel. Or you can uninstall Linkbot Labs v1.x silently based on the instructions at https://c-stem.ucdavis.edu/wp-content/uploads/2019/10/SilentInstall.pdf.




I'm having Linkbot connection issues with a Chromebook. Any suggestions?


If you run into Linkbot connection problems, first make sure you have launched Linkbot IDE on your Chromebook. Second, make sure you are running the latest version of the Linkbot IDE for Chromebooks (as listed on the Downloads page). The way to check that you have the latest version is to open up the Chrome browser and then click the "three vertical dots" menu in the upper right corner. Select "More tools" in that menu, and then "Extensions" in the submenu that appears. You should then see a list of apps and extensions that are installed on your Chromebook. Scroll down and find the one for "Linkbot IDE" and click the "Details" button. It will give you the version number and other information. If it's an old version, you can click the "Remove" button. Then go to the Downloads page and click the "Linkbot IDE" button in the Chromebook section. It should open another tab in the browser for Linkbot IDE with an "Add to Chromebook" button (assuming that you removed it). Click that and then (after some downloading) it should change to a "Launch app" button. Launch the apps and after that things should work. Note: The latest version of Linkbot IDE has the Linkbot Firmware Updater built into it. Previously they were separate, so you may have an old version of the Firmware Updater installed. Once you are running the latest version of Linkbot IDE, remove the old Firmware Updater extension.





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