Use this troubleshooting guide if your MiR250 enters Protective or Emergency stop due to an error or issue detected by the safety system. The safety system consists of the safety laser scanners and the safety PLC.

To identify if the robot is experiencing an error in the safety system, go to Monitoring > Hardware health > Safety system. If neither group beneath Safety system displays an error, the robot is experiencing another type of error that is not covered in this guide.

Before troubleshooting

• Download the documentation sheet under Download material for this guide on MiR Support Portal. Fill out the sheet as you go through the steps. If you are not able to resolve the issue and want to create a technical support ticket for MiR Technical Support, you must include a filled out sheet in your ticket. You can find the sheet under download material for this guide.

• If possible, update to the latest software. This may resolve the issue. If not, it will enable your robot to generate a more detailed error log, providing Technical Support with more information to troubleshoot the issue correctly.

• Inspect your robot for any obvious damage, such as cracks, dents, or objects stuck in the wheels.

• Open the maintenance compartments, and check the electronic components for any signs of damage. Pay attention to any parts that smell burnt and cables or connectors that have been bent, pinched, otherwise damaged, or disconnected.

• Restart the robot.

• If possible, remove any top modules from the robot, and connect an Emergency stop box.

• Check that all Emergency stop buttons are released.

Safety

Before beginning this troubleshooting guide, see the safety chapter in your MiR product's user guide or operating guide.

Accessing the internal parts

Removing the front cover

1. Unscrew the two screws holding the front cover. Use a T30 screwdriver.

   
   

2. Loosen the bottom corners one at a time by pulling out each corner.

   

3. Loosen the top corners one at the time by pulling each corner down, and then out.

   

4. Pull off the cover.

   
   

Removing the rear cover

To open the rear compartment, follow these steps:

1. Push the two white buttons on the rear cover at the same time.

   
   

2. Loosen the bottom corners one at the time by pulling out each corner.

   

3. Loosen the top corners one at the time by pulling each corner down, and then out.

   

4. Pull off the cover.

   
   

Removing the side covers

1. Turn the two screws counterclockwise with a T30 screwdriver.

   

2. Loosen the bottom corners one at the time by pulling out each corner.

   

3. Pull off the cover.

   

Removing the top cover

1. Disconnect the antennas. Unscrew the antennas from the top compartment covers and remove them.

   

2. Disconnect the antenna cables from the top cover. Unscrew the two nuts from the antenna connectors. Use a 10 mm wrench. Then, push the antenna connectors through the covers.

   

3. Remove the top compartment covers from the top plate by unscrewing the eight screws. Use a T10 screwdriver. Make sure the antenna cables are not connected to the compartment covers.

    

4. Remove the top cover from the robot by unscrewing the four screws. Use a T45 screwdriver. Make sure the antenna cables are not connected to the top cover.

    

Fault tree

Use the fault tree on the next page as an overview of the steps and solutions in this troubleshooting guide. The following points describe the meaning of each type of block in the diagram:

• At the top, you see the problem you are experiencing with your MiR product.

• The diamonds  indicate evaluation steps where a Yes or No answer leads you to the next step. Occasionally, other answers are used. Each of these steps are labeled with a letter.

• The circles  indicate disassembly or other action steps. These must be completed to access or activate certain parts of the robot to continue with the next steps. Each of these steps are labeled with a letter.

• The rectangles  indicate solutions. These describe the recommended actions to solve the initial problem. Each solution is labeled with a number.

Each step and solution are labeled to match with a more in-depth description of the task in the sections below. These descriptions are divided between Step descriptions and Solution descriptions. Many solution descriptions require the replacement of robot parts. Refer to the Spare parts list found on MiR Support Portal for the order number, or contact MiR Technical Support for further guidance—see Contacting Technical Support.

The fault tree should only be used as an overview. Make sure to read the step and solution descriptions for each step as they contain important instructions and details.

Step descriptions

What kind of issue are you experiencing?

There are three main categories of errors that the safety PLC can report in the safety system:

• Safety laser scanner issues
  If your robot disconnects constantly from the safety laser scanners or cannot read data from them, there is an issue with the safety laser scanners. You may also experience issues with the safety laser scanners detecting non-existent objects, either making the robot drive slowly or stop completely and report that its scanners are blocked.
  If you are experiencing any of the above issues, continue to step .

• Connection issues
  If the safety PLC cannot connect to the robot computer, the entire safety system is disconnected and the robot cannot run. When this happens, the robot reports the error under Hardware health > Safety system > Communication. If an error is reported in the Communication group or an error is reported regarding missing data or communication to the safety PLC, continue to step .
  
  

• Other internal issues
  The safety PLC monitors many of the internal components of the robot. If it detects an error or discrepancy in the robot system, it is reported under Hardware health > Safety system > Emergency stop. If you are not experiencing one of the issues described above, and the robot only reports an error under Emergency stop, go to solution .

Is the robot driving slowly and detecting obstacles where there are none?

While the robot is driving autonomously, open the robot interface and observe the robot's driving behavior and what obstacles it detects with the safety laser scanners.

If your robot drives irregularly, check for the following when it occurs:

• The robot often drives away from its planned path even if there are no obstacles blocking the path.

• The robot often stops for non-existent obstacles, resulting in a stop-and-go movement.
  

• There are often displayed red dots on the map where there are no actual obstacles.

These signs indicate that the laser scanners may not be operating correctly.

• If you observe the described symptoms for faulty laser scanners, go to solution .

• If you have not observed any of these issues, continue to step .

Remove the front and rear covers. What do the scanner displays show?

To complete this step, the battery must be connected, and the robot must be turned on.

The safety laser scanners have a small display port on their front that reports any internal errors with the laser scanners. To see the displays on the laser scanners, remove the front and rear covers.

Remove the front and rear covers as described in Accessing the internal parts.

The display for the front laser scanner is right above the scanner cover on the left side of the robot.

The display for the rear laser scanner is right above the scanner cover on the right side of the robot.

The display can show several different states:

• If the display shows green check marks, red crosses, or yellow warning signs, there is nothing wrong with the safety laser scanners. It is possible that there is a connection issue. Continue to step .
    

  The scanner displays show a red cross if an obstacle is detected within their Protective field set.

• If the display shows a fault with an error code, go to solution .
   

• If the display is blank and the robot is turned on, the safety laser scanner is not receiving power from the power board. Continue to step .
  

Is there a green line on the left side of the display, and can you ping the scanners?

If a scanner is disconnected from the Ethernet connection, the display will show a purple line in the upper-left corner. When the scanner is connected the line is green.

Disconnected	Connected

Check whether the scanners are connected by reading the line on the display.

To double-check the connection, try to ping the safety laser scanners. To do this, follow these steps:

1. Connect to the robot's Wi-Fi access point.

2. Open a command prompt or terminal on your computer.

3. Enter the following commands to ping the front and rear scanners respectively:

   • ping 192.168.12.10

   • ping 192.168.12.11

4. Check the replies. The following image is an example of a disconnected scanner.
   

A standard ping sends four packets on a Windows computer. If the scanners are connected, you should receive a reply for most of the messages.

• If the scanners are disconnected, continue to step .

• If the scanners are connected, go to solution .

Are the displays on both scanners off?

If a display is off, the laser scanner is not receiving power. If only one of the scanners is off, it indicates an issue with the power connection to that scanner only, but if both are off, there may be an issue with the 24 V power supply to the scanners and safety PLC.

Check if both or only one of the scanners is off.

• If neither scanner is powered, continue to step .

• If one of the scanners is powered, go to solution .

What kind of error is reported?

1. In the robot interface, go to Monitoring > Hardware health > Safety system.

2. If the robot computer is not connected to the safety PLC, it reports errors regarding missing data, false readings, or failed connections.

   

Other errors may express a faulty, invalid, or unsupported SICK program. If this kind of error is reported, the wrong SICK configuration has been applied or the configuration has been modified in an invalid way. 

• If the error describes missing data, failed readings, or missing connections, continue to step .

• If the error describes a faulty, invalid, or unsupported SICK configuration program, go to solution .

Can you ping the safety PLC?

To check if the safety PLC is on and connected to the robot system, try to ping it. To do this, follow these steps:

1. Connect to the robot's Wi-Fi access point.

2. Open a command prompt or terminal on your computer.

3. Enter the following command:
   ping 192.168.12.9

4. Check the replies. The following image is an example of a running and connected safety PLC.
   

A standard ping sends four packets on a Windows computer. If the safety PLC is connected, you should receive a reply for most of the messages.

• If the PLC is disconnected, continue to step .

• If the PLC is connected and the previous step was , go to solution .

• If the PLC is connected and the previous step was , go to solution .

Access the safety PLC and power board

There are two ways to access the safety PLC and power board. The first method is easier and there is less risk of damage and unnecessary wear to robot components. The second method requires more disassembly but enables better access to the power board and safety PLC. Only apply the second method if you are not able to perform the necessary troubleshooting steps after applying the first method.

Method 1 (recommended)

1. Remove the rear cover as described in Removing the rear cover.

2. Remove the two small screws from the battery fast-swap assembly. Use a T20 screwdriver. These screws may already be removed if you have enabled the fast-swap feature described in the user guide.
   

3. Gently, pull out the battery. This will enable you to lift the battery plate slightly to better access the power board cables.
   

4. Remove the two center screws using a T30 Torx screwdriver. When reassembling the robot, tighten these screws to 8 Nm.
   

5. Remove the four outer screws. Use a T30 screwdriver. When reassembling the robot, tighten these screws to 8 Nm.
   

6. Unplug the status light cable.
   

7. Gently, remove the battery fast-swap assembly from the robot. You can now access the power board and safety PLC.
   

If the previous step was or the robot needs to be powered to complete the step, continue to step .

Method 2 (use only if necessary)

1. Remove the top cover as described in Removing the top cover

2. Pull out the battery. Be sure to handle the battery gently.

   

3. Unscrew the two screws on the battery plate. This will enable you to remove the plate where the safety PLC is mounted.

   

4. Remove the plate beneath the battery that the safety PLC is mounted to. To remove the plate, lift the plate approximately 3 cm, and then pull it 5 cm towards the rear end of the robot.

    

5. Tilt the plate upwards and place it a the rear end of the robot.

   If you don't have anyone to help you hold the safety PLC plate, place an object beneath the safety PLC to support it.

   
   

If the previous step was or the robot needs to be powered to complete the step, continue to step .

Connect a 3 A MiR cable charger to a power supply and then the robot

To connect the robot to a power supply, first connect a MiR Cable Charger Lite 48V 3 A to a power supply, and then connect the other end to the robot's charging interface.

Once the charger begins powering the robot, the robot will turn on.

If the previous steps were and , continue to step .

Is the safety PLC receiving power?

The safety PLC is located behind the battery connector and receives power from the power board below it.

To check if the safety PLC is receiving power, check if any of the diodes are lit. If they are, the PLC is powered.

• If any of the diodes are lit in the safety PLC, go to solution .

• If none of the diodes are lit, continue to step .

Is the robot running software version 2.10.4 or higher?

Software 2.10.4 introduced a system log message that indicates whether the power board is providing 24 V to the safety PLC.

To see which software version your robot is running, sign in to the robot interface, and either look in the bottom-left corner or go to Help > Robot information. The software version is displayed under Robot software version.

• If your robot is running software version 2.10.3 or lower, continue to step .

• If your robot is running software version 2.10.4 or higher, continue to step .

Under Hardware health > CAN communication bus > Can node 21 is the status OK?

Under Hardware health > CAN communication bus > Can node 21, you can see if the 24 V power supply from the power board is disconnected or faulty. If the status is node is OK, the power board is able to provide a 24 V power supply. If not, there may be a fault in the power board.

• If Can node 21 has the status OK, continue to step .

• If Can node 21 has a disconnected status, go to solution .

Restart the robot. In the system log, is Iso24VPlc: PGood failed shown after startup?

Turn the robot off and then on again. Once the robot has started up, sign in to the robot interface, and go to Monitoring > System log.

Search through the log for the message: Iso24VPlc: PGood failed. This message indicates that the power board is not providing 24 V to the safety PLC.

• If you find the message, continue to step .

• If you don't find the message, continue to step .

Unplug the PLC power connector and measure the voltage between pins 1 and 2, 3 and 4, and 5 and 6. Is there 24 V between all pins?

Unplug the PLC power connector. This is the 6-pin Molex connector with the red and black wires.

The pin numbers for the connector when it is connected to the safety PLC connector socket are shown below. Each odd number pin is connected to a red wire, and the even number pins are connected to black wires.

Measure the voltage between the following pairs of pins:

• 1 and 2

• 3 and 4

• 5 and 6

• If you measure 24 V between all pairs of wires, continue to step .

• If any of the pairs does not have 24 V between them, go to solution .

Unplug the PLC power connector and measure the resistance between pins 1 and 2, 3 and 4, and 5 and 6 in both connectors. Is there approximately 0 Ω across any pairs of pins?

If you have not already done so, unplug the PLC power connector. This is the 6-pin Molex connector with the red and black wires.

The pin numbers for the connector when it is connected to the safety PLC connector socket is shown below. Each odd number pin is connected to a red wire, and the even number pins are connected to black wires.

Measure the resistance between the following pairs of pins on both the socket to the safety PLC and the connector to the power board:

• 1 and 2

• 3 and 4

• 5 and 6

If you measure approximately 0 Ω (+5 Ω) across a pair of pins, it indicates that there is a short circuit.

• If you measure 0 Ω across any pairs of pins on the power board cable connector, go to solution .

• If you measure 0 Ω across any pairs of pins on the PLC connector socket, go to solution .

• If you don't measure 0 Ω across any pairs of pins either connector, go to solution .

Is the false scanner data very close to the scanner when there are no other obstacles within one meter of the robot?

Drive the robot to an area where it has a cleared area in a one meter radius around it. Make sure there are no reflective or transparent obstacles around the robot that are within the laser scanners' range.

In the robot interface, go to Monitoring > Safety system, and observe the scanner data (red dots).

• If there is false scanner data close to the laser scanners, go to solution .

• If the red dots aren't present and only appear in certain areas or while the robot is transporting a shelf, go to solution .

Access the control panel PCB board

To access the control panel PCB board loosen the two screws on each side of the corner.

Screw in the black set screw to release the bumper, and lift the bumper up.

Read the safety PLC status from SICK Safety Designer

Instead of disassembling the robot to access the safety PLC, you can use SICK's Safety Designer program to read the statuses from the safety PLC. You can download this program from SICK's official website.

To open the safety PLC overview, follow these steps:

1. Connect to the robot's Wi-Fi access point.

2. Open the Safety Designer program and select Search for devices.
   

3. Double-click on the safety PLC module, or drag the module into the main window.
   

4. Double-click on the safety PLC module in the main window to open the current configuration on the PLC.

   A digital overview of the safety PLC is displayed. You can use this to read which signals the safety PLC is sending and receiving.

   

Solution descriptions

Check the laser scanners for damage and replace the optics cover if necessary

If red dots are often displayed close to the laser scanners when no other obstacles are close by, it may be due to damage or contamination on the laser scanner optics cover or an internal issue with the scanner. Apply the following solutions in their given order and test if any of them resolve the issue:

• Clean the laser scanner optics cover as described in the user guide.

• Check the laser scanner optics cover for damage, such as scratches, and replace the cover if you find any damage.

• Replace the laser scanner.

Remove or cover up reflective or transparent material at 200 mm height

If the red dots are often shown further away from the robot and the issue only occurs in certain areas or when the robot is transporting a shelf, the issue may be due to reflective or transparent material interfering with the scanners.

To reduce the frequency and effect of the issue, remove or cover up any reflective or transparent surfaces at 200 mm height in the robot's work environment. If your MiR250 is used to transport shelves, it can be especially helpful to apply gray, matte material to the shelf legs at 200 mm height.

Check the Ethernet connection to the disconnected scanner

If a safety laser scanner is disconnected from the Ethernet, the robot will report disconnection errors.

The following sections describe how to check the cables for the front and rear safety laser scanners.

Rear scanner

1. Remove the Fast-swap battery plate to access the safety PLC as described in step .

2. On the safety PLC, check the Ethernet connector in port 2. This is the cable that connects to the rear scanner.

   

3. If the cable seems fine, check the connectors on the safety laser scanners. To access the connectors, see the guide How to replace the safety laser scanners on MiR250. If all connectors seem fine, there may be an issue with the cable from the laser scanner to the PLC or the port in the PLC.

4. Test the cable between the laser scanner and the PLC by disconnecting the cable from the PLC and plugging it directly into the router or switch.

   1. On MiR250 hardware version 1.0, disconnect the PLC from the router in port 1 and plug the cable from the laser scanner into that port.

      

   2. On MiR250 hardware version 2.0, disconnect the top interface from port 3 on the switch and plug the cable from the laser scanner into that port.

      

If the diode on the router or switch lights up when the scanner is connected, there is an issue with the port in the safety PLC. Replace the safety PLC.

If the diode does not light up, the cable to the laser scanner must be replaced.

Front scanner

1. Remove the front, rear, and right side covers as described in Accessing the internal parts.

2. On the router or switch, check if there is an active connection to the front scanner. The diode for the port should light up to indicate an active connection.

   1. On MiR250 hardware version 1.0, the front scanner is connected to port 4 on the router.

      

   2. On MiR250 hardware version 2.0, the front scanner is connected to port 1 on the switch.

      

3. If all of the diodes are lit, go to solution . If one of the other diodes isn't lit, the Ethernet cables may have been swapped. Inspect the connector and cable plugged into the port that does not have a connection. If the connector and cable seem fine, check the connector on the rear safety laser scanner. To access the connector, see the guide How to replace the safety laser scanners on MiR250.

Generate a SICK report and contact MiR Technical Support

Issues in the safety system are logged in SICK reports that MiR Tech Supporters can use to diagnose the issue. To generate a SICK report, see the guide How to generate a SICK report. Send the report to MiR Technical Support as described in Contacting Technical Support.

If the fault is F2, update to 2.10.3. For any other fault, see Fault indication on the display in SICK's nanoScan3 documentation

F2

Most often, this issue occurs when an object is placed just on the border of the active Protective field for a long period of time, for example, if the robot has been left in a charging station or other parked position close to a fixed structure.

Restarting the robot will resolve the immediate issue, but if the robot is left in the same position again for a long time, the issue will reoccur. If the issue continues to reoccur, update the robot software to 2.10.3.1 or higher, and apply the latest SICK configuration file from the software—see the guide How to apply the default SICK configuration on MiR250, MiR500, MiR600, MiR1000, and MiR1350.

Other errors

In SICK's documentation for the nanoScan3 safety laser scanners, the section Fault indication on the display provides a table of all the faults the scanner can display and what the causes and solutions are for each fault. Try to resolve the issue using the information provided in this guide.

Check the plug connected to the laser scanner

If one of the laser scanners is not powered, it indicates that there is only a fault in the connection to that scanner. The fault will likely be on the end of the cable connected to the laser scanner. If the other end is damaged, most likely the safety PLC and other laser scanner would also not be receiving power.

To access the laser scanner connectors, see the guide How to replace the safety laser scanners on MiR250.

Ensure that the connector and cable are intact and are securely connected to the safety laser scanner. If the cable seems damaged, replace it.

If the cable seems fine, it is also possible that the safety laser scanner itself needs to be replaced. Generate a SICK report—see How to generate a SICK report—and contact MiR Technical Support for help determining if there is an issue with the scanner itself—see Contacting Technical Support.

There is an issue in the power board. Contact Technical Support

There is an internal hardware of software issue in the power board. Report your case to MiR Technical Support as described in Contacting Technical Support.

Check the cables from the safety PLC connectors to the power board

The power board powers the safety PLC and safety laser scanners with 24 V from the J3 socket on the power board.

The cables that connect the power board to the safety PLC are collected inside the cable harness. You cannot check the cables themselves, but you can inspect the connectors.

Check the connector in the J3 socket on the power board. Make sure it is correctly plugged in, and pull the cable lightly (max 10 Nm) to check that it is connected to the connector.

Repeat the same process with the safety PLC connectors.

If any wires are loose, you can try to push the wire back in place. If this is not possible, you must replace the cable.

Check the wires from the safety PLC connectors to the safety PLC

The wires that connect power to the safety PLC are the red and black wires that connect to terminals A1 and A2 on each PLC module.

Check that these wires are securely connected by pulling lightly on each of them (maximum 10 N). If they are not connected securely, press the release button next to the terminal and firmly push the wire back in place.

If all of the wires are securely connected, check each wire for any signs of damage. If you find a damaged wire, replace it.

Upload a new standard SICK configuration file

The SICK configuration file your robot is using may not be the correct one or it may have been corrupted. Apply a new SICK configuration by following the guide How to apply the default SICK configuration on MiR250, MiR500, MiR600, MiR1000, and MiR1350.

Check the Ethernet cable from the router or switch to the safety PLC

If the robot computer cannot connect to the safety PLC, the Ethernet cable from the router to the PLC may be disconnected or damaged.

1. Remove the front, rear, and right side cover as described in Accessing the internal parts.

2. Check that there is a connection to the safety PLC.

   1. On MiR250 hardware version 1.0, the robot computer and safety PLC are connected with an Ethernet cable via the router. Check that the diode for port 1 on the router lights up. This indicates that there is a connection to the safety PLC.

      

      If all connectors seem fine, check that the entire cable is intact. Replace the cable if you find any signs of damage.

      If the cable seems fine, you can try to replace the cable with one that you know works.

      Do not fit the cable into the robot when you are testing another cable. Just plug it into the two ports to determine if it resolves the issue, and if it does, replace the old Ethernet cable with the new one.

   2. On MiR250 hardware version 2.0, the safety PLC is connected directly to the robot computer with an Ethernet cable in the robot computer's second Ethernet port. Test the cable by unplugging it from the robot computer and connecting it to port 1 on the switch. If the corresponding diode on the switch lights up, the Ethernet cable is working.

      

   3. If there is still no connection to the safety PLC, generate a SICK report—see How to generate a SICK report, and contact MiR Technical Support as described in Contacting Technical Support

3. If all of the diodes on the router or switch are lit, go to solution .

4. If one of the other diodes is not lit, the Ethernet cables may have been swapped.

5. Inspect the connector and cable plugged into the port that does not have a connection. If the connector and cable seem fine, check the Ethernet connector in port 1 on the safety PLC. This is the cable that connects to the router.

   

See the solution description for an overview of solutions to other possible issues

E-stop restart required

1. When this field is True, press the Resume button on the control panel to reset the safety system and enable the robot to operate again. If the field continues to be True after pressing the Resume button, check the other fields under Safety system for other faults.

   If there is nothing wrong in the other fields, the Resume button may be disconnected.

2. Connect to the safety PLC using Safety Designer as described in step . Check if the diode I3 on the XTIO 1 safety PLC module lights up each time you press the Resume button.

   

   If not, the button is disconnected and you should check the following:

   1. On the control panel PCB board, unplug the connector in the J1 socket and measure the voltage relative to ground from pin 9 in the socket.
      

   2. Press the Resume button. You should measure 24 V from pin 9 each time the button is pressed. If not, check the cable labeled CAB-051 that connects the Resume button to the PCB board that controls the buttons.
      

   3. If you do measure 24 V, the connection is broken between the PCB board and the safety PLC. Reconnect the connector in the J1 socket and check the safety PLC connectors.
      

Emergency button

If this field is Pressed, the Emergency stop circuit is not closed. To determine the fault, follow these steps until one of the steps resolves the issue:

1. If you have not already done so, disconnect your top module and connect an Emergency stop button box to the robot's Auxiliary emergency stop interface instead.

2. Release the Emergency stop button and press the Reset button on the Emergency stop box.

   If the issue is only present when a top module is mounted to the robot, the Emergency stop circuit in the top module is broken. Contact your top module distributor for assistance.

3. Connect to the safety PLC using Safety Designer as described in step .

4. Check if the diodes for I1 and I2 on the XTIO 1 safety PLC module are lit.

   

5. If I1 or I2 are off, there is a broken connection in the Emergency stop circuit. Follow these steps to find where the disconnection is:

   1. Pull the wires that connect to the X1, X2, I1, and I2 on the XTIO 1 safety PLC module with a maximum force of 10 N. If the wire is loose, press the release button above the terminal on the PLC with a thin tool and push the wire back in place.

   2. Disconnect the wires in X1 and X2, and measure the voltage relative to ground from the X1 and X2 terminals in the safety PLC. If they don't measure 24 V, there is a fault in the safety PLC.

   3. Reconnect the wires in the safety PLC, and check that the large safety PLC connectors are securely connected.

      

   4. Unplug the Emergency stop button box, and measure the voltage relative to ground from pins 2 and 3 in the Auxiliary emergency stop interface.

      

   5. They should both measure 24 V. If not check the connections beneath the interface.

      

   6. Connect the Emergency stop button box again, and press the Reset button.

   7. Measure the voltage relative to ground of the wires that connect to the I1 and I2 terminals on the XTIO 1 safety PLC module. If they both measure 24 V, but the I1 and I2 diodes aren't lit when the wires are plugged in, there is a fault in the safety PLC. If one of the wires does not measure 24 V, there is an issue in the cable harness or safety PLC connectors.

Restart button

If this field is Pressed even if you are not pressing the Resume button, the button is either stuck, or there is a short circuit that has the same effect as the button being pressed all the time.

If the button is not stuck, check the cables as described in E-stop restart required.

Stop button

If this field is Pressed even if you are not pressing the Stop button, the button is either stuck, or there is a short circuit that has the same affect as the button being pressed all the time.

1. Check that the button is stuck. If it is, and you can't get the button unstuck, replace the control panel.

2. Connect to the safety PLC using Safety Designer as described in step .

3. Check if the diode I6 on the XTIO 1 safety PLC module turns off each time you press the Stop button.

   

If it doesn't, the connection from the button to the safety PLC may be short-circuited and you should check the following:

1. On the control panel PCB board, unplug the connector in the J1 socket and measure the voltage relative to ground from pin 10 in the socket.

   

2. Press the Stop button. You should measure 0 V from pin 10 each time the button is pressed and 24 V when it is not. If not, check the cable labeled CAB-050 that connects the Stop button to the PCB board that controls the buttons.

   

3. If you do measure 0 V, the connection is short circuited between the PCB board and the safety PLC. Reconnect the connector in the J1 socket and check the safety PLC connectors.

   

STO Feedback

If the field is not OK, the STO feedback is indicating that the STO contactors are not operating correctly.

1. Connect to the safety PLC using Safety Designer as described in step .

2. Check if the diode I4 on the XTIO 1 safety PLC module is lit. If not, there is a broken connection in the STO feedback circuit.

   

While the robot is in Protective stop, measure the voltage relative to ground from the following terminals:

• Terminal 22 in contactor K1.

  • If it does not measure 24 V, the connection to the power board is broken, or there is a fault in the power board.

• Terminal 21 in contactor K1.

  • If it does not measure 24 V, there is a fault in the contactor. You can try tapping it gently to release the switch. If the issue persists, replace the contactor.

• Terminal 22 in contactor K2.

  • If it does not measure 24 V, the connection to the K1 contactor is broken.

• Terminal 21 in contactor K2.

  • If it does not measure 24 V, there is a fault in the contactor. You can try tapping it gently to release the switch. If the issue persists, replace the contactor.

• If all of the contactors measure 24 V, unplug the wire from terminal I4 in the XTIO 1 safety PLC module and measure the voltage from the wire relative to ground.

  • If it does not measure 24 V, the connection to the STO contactors is broken.

  • If it does measure 24 V, and the I4 diode does not light up when you plug it in again, there is a fault in the safety PLC.

Mechanical brake feedback

If the field is not OK, the mechanical brake feedback is indicating that the mechanical brake relay is not operating correctly.

1. Connect to the safety PLC using Safety Designer as described in step .

2. While the mechanical brakes are engaged, check if the diode I5 on the XTIO 1 safety PLC module is lit. If not, there is a broken connection in the mechanical brake relay feedback circuit.

   

The mechanical brake relay is attached to the control panel PCB board.

1. To determine if the PCB board needs to be replaced, unplug the connector in the J1 socket and measure the voltage relative to ground from pin 7 in the socket.

   

   Check that the power cable for the PCB board and the small relay on top of the board are properly connected.

2. When the brakes are engaged, you should measure 24 V. If not, the relay is not operating as expected, and should be replaced. If you do measure 24 V, check the K3 contactor on the side of the robot.

Safe stop violation (SS1)

If the field is not OK, the dynamic brakes are not stopping the robot within the expected time limit. This is determined by feedback from the motor encoders. When the dynamic brake function doesn't stop the robot in time, the mechanical brakes are activated instead. If this error keeps occurring, over time, the mechanical brakes will wear down from unintended use.

There are several reasons this error may occur:

• The robot is transporting a load that exceeds its total payload, or the center of mass of the load is outside the permitted area—see your robot's user guide for the permitted CoM of the robot's load and total payload.

• The robot is driving down a slope that is steeper than the permitted gradient—see the product page on MiR website for slope specifications.

• One of the connections to the SS1 contactors may be broken. You can try to localize the issue to one of the motors by observing if the robot veers to one side when braking. Once you have determined on which side the issue is, remove the cover on that side—see your robot's user guide—, and check the following components on that side: 

  • The SS1 contactor (make sure all the cables are connected securely)
    
    

  • The motor cable (CAB-037 on left side and CAB-038 on right side)

  • The motor itself (make sure the motor can turn the drive wheel evenly and without significant vibrations)

Safe guard stop enabled

If the field is True, the Safeguarded stop Auxiliary safety function is activated. For more information about the function, see the Safety system section in your robot's user guide.

If the function signal is not working as intended, disconnect your top module and connect pins 1 to pins 2 in both Auxiliary safety functions interfaces.

If the field still shows True, there is an issue with the connection between the top interface and the safety PLC.
If the field shows False, there is an issue with the connected top module. Contact your top module distributor for further assistance.

Shared E-stop input

If the field is True, the Shared E-stop Auxiliary safety function is activated. For more information about the function, see the Safety system section in your robot's user guide.

If the function signal is not working as intended, disconnect your top module and connect pins 3 to pins 6 in both Auxiliary safety functions interfaces, and verify that the Shared E-stop output field further down the list is displaying the status False.

• If the field still shows True, there is an issue with the connection between the top interface and the safety PLC.

• If the field shows False, there is an issue with the connected top module. Contact your top module distributor for further assistance.

Limit speed input

If the field is True, the Reduced speed Auxiliary safety function is activated. For more information about the function, see the Safety system section in your robot's user guide.

If the function signal is not working as intended, disconnect your top module and connect pins 1 to pins 4 in both Auxiliary safety functions interfaces.

• If the field still shows True, there is an issue with the connection between the top interface and the safety PLC.

• If the field shows False, there is an issue with the connected top module. Contact your top module distributor for further assistance.

Manual mode engaged

If the field is On, the Operating mode key has been turned to Manual mode. You must press the Resume button after changing modes to bring the robot out of Protective stop.

If you have tried to change modes with the Operating mode key and the robot does not respond, you must access the control panel PCB board—see step .

Check the following components:

• CAB-053 that connects the dial to the control panel PCB board
  

• The PCB board

• The CAB-002 cable connector in the J1 socket of the PCB board

Manual brake release switch

If the field is On, the Manual brake release switch has been turned to the On position and the brakes are released. Turn the switch counter-clockwise to activate automatic handling of the brakes.

If the issue persists, try to push the robot.

• If you can push the robot easily, the brakes are still released and there is a problem with one of the following components:

  • The Manual brake release switch

  • CAB-047 that connects the switch to the control panel PCB board—to access the PCB board, see step

  • The PCB board

• If you can't push the robot easily, but the robot interface still displays that the Manual brake release switch is on, there is a problem with the connection from the control panel PCB board to the safety PLC. Inspect the following:

  • CAB-002 cable connector in the J1 socket of the PCB board

  • The safety PLC connectors
    

  • The wire connected to terminal I8 in the XTIO 2 safety PLC module—to access the safety PLC, see step

Shared E-stop output

If the field is True, the robot is in Emergency stop and is signaling this to the top module through the Shared E-stop interface. For more information about the function, see the Safety system section in your robot's user guide.

If the robot is in Emergency stop when it shouldn't be, check the Emergency stop circuit as described in Emergency button.

Locomotion output

If the field is True, the robot is driving and is signaling this to the top module through the Locomotion interface. For more information about the function, see the Safety system section in your robot's user guide.

If the function is not working as intended, measure if 24 V is delivered from pins 5 in the Auxiliary safety functions interfaces relative to ground while the robot is standing still. If they don't, there is an issue with the connection between the top interface and the safety PLC.

Turn speed violation

If the field is not OK, the robot has turned too quickly. If the issue keeps reoccurring, there may be an issue in the motors or motor controller carrier board. Inspect the motor controller carrier board for any disconnected or loose connections.

Forced stop

If the field is True, the mechanical brakes or the safety contactors have stopped the robot. This can happen due to various safety issues. Check the other fields under Safety system for other faults.

Manual mode reset required

If the field is True, you have turned the Operating mode key to another mode. Press the Resume button to get the robot out of Protective stop.

If the robot does not respond, try turning the Operating mode key to another mode. If the robot does not respond, see the solution in Manual mode engaged.

If the robot can change to another mode, but does not get out of Protecitve stop when you press the Resume button, see the solution in Restart button.

Software Manual mode engaged

If the field is True, you have engaged Manual mode in the robot interface. Turn the Operating mode key to Manual mode, and press the Resume button to get the robot out of Protective stop.

E-stop input status

If this field is not OK, one of the Emergency stop circuits is broken. Check the circuit as described in Emergency button.

Safe guard stop input status

If this field is not OK, one of the Safeguarded stop circuits is broken. Test the circuit as described in Safe guard stop enabled.

Shared E-stop input status

If this field is not OK, one of the Shared E-stop circuits is broken. Test the circuit as described in Shared E-stop output.

Reduced speed input status

If this field is not OK, one of the Reduced speed circuits is broken. Test the circuit as described in Limit speed input.

I/O module 1/2/3/4 output status

If this field is not OK, there is a fault in the power input or output terminals of the XTIO 1, XTIO 2, XTIO 3, or XTIO 4 safety PLC module. This can be due to short circuit in the ground connection or 24 V power supply.

If the issue is only localized to one of the PLC modules, check that the wires connected to terminals A1 and A2 in the faulty XTIO module are securely connected. If they aren't, press the release button next to the terminal and firmly push the wire back in place.

If none of the PLC modules are powered, see solution .

Laser (Front) contamination error

If this field is True, the front safety laser scanner is reporting a contamination error. Clean the laser scanner as described in your robot's user guide.

If the issue persists, check the scanner cover for scratches or other damage that may affect the scanner performance. If the cover is damaged, you must replace it.

Laser (Front) device error

If this field is True, the front safety laser scanner is reporting a device error. To determine what kind of error and what to do, go to step , and continue from there to fix the issue.

Laser (Front)

If this field is Blocked, the front laser scanner is detecting an obstacle within its active Protective field. Check if there are any obstacles close to your robot that may be triggering the safety laser scanner. If not, clean the cover glass as described in your robot's user guide.

If the issue persists, check the scanner cover for scratches or other damage that may affect the scanner performance. If the cover is damaged, you must replace it.

If you cannot find any obvious faults in the scanner cover, follow the steps from step .

Error in STO feedback from top module

This error is only applicable if the robot has a MiR Shelf Carrier 250 mounted to it. This error occurs if there is a fault in the feedback from the STO contactor in the top module.

To resolve this issue, remove the top cover from MiR Shelf Carrier 250 by unscrewing all 14 bolts in the top cover.

Check the STO contactors, the wires connected to them, and the cables to the GPIO and Auxiliary safety functions interfaces. If the contactors or cables are damaged or faulty, replace them.

Laser (Back) contamination error

If this field is True, the rear safety laser scanner is reporting a contamination error. Clean the laser scanner as described in your robot's user guide.

If the issue persists, check the laser scanner cover for scratches or other damage that may affect the scanner performance. If the cover is damaged, you must replace it.

Laser (Back) device error

If this field is True, the rear safety laser scanner is reporting a device error. To determine what kind of error and what to do, go to step , and continue from there to fix the issue.

Laser (Back)

If this field is Blocked, the rear laser scanner is detecting an obstacle within its active Protective field. Check if there are any obstacles close to your robot that may be triggering the safety laser scanner. If not, clean the cover glass as described in your robot's user guide.

If the issue persists, check the scanner cover for scratches or other damage that may affect the scanner performance. If the cover is damaged, you must replace it.

If you cannot find any obvious faults in the scanner cover, follow the steps from step .

Max speed violation

If this field is not OK, the motor encoders have registered that the maximum speed that the robot is permitted to drive has been exceeded.

There are several reasons this error may occur:

• The robot is transporting a load that exceeds its maximum payload, or the center of mass of the load is outside the permitted area—see your robot's user guide for the permitted CoM of the robot's load and total payload.

• The robot is being pushed while operating resulting in it driving faster than expected.

• The robot is driving down a slope that is steeper than the permitted gradient—see the product page on MiR website for slope specifications.

Low speed violation

If this field is not OK, the motor encoders have registered that the robot is driving much slower than expected.

There are several reasons this error may occur: 

• The robot is transporting a load that exceeds its maximum payload, or the center of mass of the load is outside the permitted area—see your robot's user guide for the permitted CoM of the robot's load and total payload.

• There is an obstacle that is blocking the robot and slowing it down. This could, for example, be an object that is blocking one of the wheels or an object that is outside the field of view of the robot and is in the way of the robot's load or top module.

• The robot is driving up a slope that is steeper than the permitted gradient—see the product page on MiR website for slope specifications.

Encoder error

If this field is True, the encoder is reporting an internal motor encoder error. Inspect the bogies, motors, gearboxes, and SICK Motion controller module for anything that may be causing the error. If you cannot find any faults, contact MiR Technical Support as described in Contacting Technical Support.

Left motor encoder

Use this field to localize an encoder error to the left motor—see Encoder error.

Right motor encoder

Use this field to localize an encoder error to the right motor—see Encoder error.