The safety PLC is responsible for controlling the safety system in MiR250. If your robot keeps reporting errors in the safety system, and all of the other safety related components are functioning correctly, there may be a problem with the safety PLC.

Things you'll need

• A safety PLC mounted to a battery plate from MiR

• A pair of pliers or scissors to cut cable ties

• Cable ties

• T30 and T10 screwdrivers

• A 15 Nm torque wrench with a T45 head

Before replacing the safety PLC

Step 1: If the safety PLC spare part you have received includes a MOC module at the end, remove the module. To do this, follow these steps:

1. Determine if the PLC stack includes a MOC module at the end. If not, skip the rest of this step.
   
   

2. If there is a MOC module, remove the end stop next to it.
   

3. Slide the MOC module off of the PLC stack, and discard it. Keep the end stop off. Later, you will need to slide the MOC module from the other safety PLC on.
   

Step 2: Turn off the robot and disconnect the battery. To disconnect the battery, follow these steps:

1. Remove the rear cover by pressing the two white buttons and pulling off the cover. When removing the cover, un-click the two bottom corners first and then the two top corners.
   
2. Turn the Battery lock switch clockwise to release the Battery lever.
   
3. Pull the Battery lever down to disconnect the battery.
   
4. Turn the Battery lock switch counter-clockwise to lock the battery lever again.

Step 3: Disconnect the antennas. Unscrew the antennas from the top compartment covers and remove them.

Step 4: Disconnect the antenna cables from the top cover. Unscrew the two nuts from the antenna connectors using a 10 mm wrench, and push the antenna connectors through the covers.

Step 5: Remove the top compartment covers from the top plate by unscrewing the eight screws with a T10 screwdriver. Make sure the antenna cables are not connected to the compartment covers.

Step 7: Pull out the battery. Be sure to lift the battery over the rear status light, and then pull it out gently.

Step 8: Unscrew the two screws on the battery plate. This will enable you to remove the plate where the safety PLC is mounted.

Step 9: 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. You should then be able to tilt the plate upwards and place it at the rear end of the robot.

Replacing the safety PLC

Step 1: Label the safety PLC cables so you can connect them in the same order on the new PLC.

Step 2: Cut all of the cable ties fastening the cables to the cable plate, and unplug the cables.

Step 3: Label the Ethernet cables so you can connect them to the same ports on the new PLC.

Step 4: Unplug the Ethernet cables.

Step 5: Remove the end stop from the top end of the DIN rail with the PLC modules.

Step 6: Gently, slide the MOC module off of the DIN rail, without twisting or applying tension to the connected MOC cable. It is important that the MOC cable is disturbed as little as possible.

Step 7: Remove the plate with the safety PLC from the robot. Check that there are no cables connected to the PLC.

Step 8: Place the new safety PLC and plate at the rear end of the robot like you did with the old PLC, and reconnect the cables. Use your labels and the images in the previous steps to determine the correct socket for each connector.

Step 9: Use cable ties to keep the safety PLC cables organized and securely fixed to the safety PLC cable plate.

Step 10: Slide the MOC module back onto the DIN rail, and mount the end stop securely against the MOC module.

Step 11: Reassemble the robot by following the steps in Before replacing the safety PLC in reverse.

Testing

Turn on the robot, and sign in to the robot interface. Go to Monitoring > Hardware health, and verify that there are no errors under Safety system.