Practical Maintenance and Troubleshooting of KUKA KR C5 slim-2 Controller

The KUKA KR C5 slim-2 Controller is a controller platform designed for small robots, compact workstations, and cabinet slide in installations. It supports up to 6 servo axes, weighs approximately 18 kg, has a protection level of IP20, noise level below 71 dB (A), power supply of AC 3 × 380 V, 400 V, 415 V, 440 V or 480 V, three-phase four wire, grounded neutral point, allowable deviation ± 10%, rated connected load 5.00 kVA, system impedance not greater than 300 m Ω, ground leakage current not greater than 150 mA, line side fuse minimum 3 × 10 A, maximum 3 × 16 A slow melting, frequency 49 to 61 Hz, thermal output 440 W. For on-site engineers, the difficulty of KR C5 slim-2 lies not in "wiring power on", but in the coordination between control unit and power unit, default allocation of safety interface, The logic of load voltage for USS 2, the replacement sequence of sliding in modules, and how to quickly locate faults from the power supply, safety chain, communication chain, and cooling chain. This article focuses on maintenance and troubleshooting.

Control unit, power unit, and cooling

The KR C5 slim-2 consists of a control unit and a power unit. The control unit, also known as the control box, contains KAI board (optional), button battery, NextGen system board, IFBstd standard interface board, IFBsafe safety interface board, and internal fan inside. The NextGen system board is a control computer responsible for graphical interfaces, program creation and modification, path planning, sequence control, drive loop control, monitoring, safety device communication, and external device communication. IFBstd provides non secure digital I/O, IFBsafe provides secure I/O, and IFBsafext provides extended secure I/O required for SafeOperation. KAI board is used for artificial intelligence and vision applications, with optional 4GB or 8GB versions, providing additional Ethernet interfaces. The power unit consists of a radiator, KSP drive controller, FCU, SCU, and PSU, responsible for generating intermediate circuit voltage and system voltage, controlling motors, controlling brakes, and checking intermediate circuit voltage in braking mode. The power unit is not allowed to be opened arbitrarily, otherwise it may cause serious injury or property damage.

Cooling is achieved by a fan, with air entering through the inlet and exiting through the outlet. The front and rear must be kept in contact with cooling air. If installed in a compactcab or smallizecab, the air inlet and outlet should not be blocked, otherwise it may cause unexpected shutdown and shorten the lifespan. In terms of environmental conditions, the operating temperature ranges from -5 ℃ to+45 ℃, the storage and transportation temperature ranges from -20 ℃ to+40 ℃, and can reach -25 ℃ to+70 ℃ without batteries. The maximum temperature change is 1 K/min, with no derating below an altitude of 2000 meters, and a derating of 5% per 1000 meters between 2000 and 3000 meters. Pollution level 2, relative humidity 5% to 95%, condensation is not allowed. Vibration operation 0.5 g, transportation 0.5 g; impact operation 2 g, transportation 10 g, half sine 11 ms. If the mechanical stress is greater, anti vibration components must be installed.

Interface layout and security chain

The connection panel of KR C5 slim-2 depends on the installed board and the number of robot axes. The standard interfaces include: XGSD for microSD card, XFUSB1 and XFUSB3 for USB 3.0, XG19.1 for teaching pendant, XD12 and XD12.1 for 24V power supply, XG12 provides 16 non safety digital inputs and 16 non safety digital outputs, XG11.3 provides 8 safety inputs and outputs, XG11.1 provides 3 safety inputs and 1 safety output, XG11.2 is used to control the US2 peripheral contactor, XG42 provides 1 safety input for reference switch, XG58 provides 2 safety inputs, XG33 provides 4 fast measurement inputs and 1 drives ready light output, XF21 is used for RDC or TPC, XF21.1 is used for external shaft drive box, XD20.1 XD20.6 is used for motor interface, XD10.1 and XD10.2 are used for brake interface, XD55 provides 27 V internal power supply, and XD60 is used for future applications. The rear panel includes XD2 for UPS and battery testing synchronization, X1003 for cabinet fans, XD1 for power connections, and XD3 for braking resistors.

The network interface depends on the hardware. When adding an Ethernet expansion board to the NextGen system board, XF1 is KSI, XF2 is ONI/KLI/KLI2, XF3 is KEI, XF4 is KLI, XF5 is OLI, XF6 and XF7 are OSI, and XF8 and XF9 are KLI/KLI2/RNET. When adding KAI board to NextGen, XF10 to XF12 are KAI interfaces. The KSI interface must not be connected to IT networks, with a maximum cable length of 100 meters. The KLI can be connected to OT or IT networks for PLC, terminals, update services, and diagnostics. KEI is used for external EtherCAT slave stations, and EtherCAT devices must be configured using engineering tools. The input and output of XG12 can be switched between high side or low side in groups of 8. Default high side, power supply provided through XD12, must use safely isolated PELV/SELV power supply, rated 24 V ± 10%, maximum insurance 10 A.

The secure interface is a key focus on site. The default allocation for XG11.1 is: safety output 1 is local emergency stop, safety input 1 is external emergency stop, safety input 2 is operational safety, and safety input 3 is not used. XG11.3 provides 5 secure inputs and 3 secure outputs, which can be freely configured. XG13.1 and XG13.2 are used for SafeRangeMonitoring, SafeOperation, and SafeSingleBrake, and need to be configured before use. XG58 is used for external enable switches and additional emergency stops, and can also be used as a reference switch. The secure input adopts a dual channel design with external testing and loop detection shutdown capability. The test outputs TA_S and TA_S are alternately turned off, with a turn off pulse length of 600 μ s, a single channel turn off period of less than 1 second, and a 50 ms offset between the two channels. The input channel N_A [x] must be powered by TA_S, and N_B [x] must be powered by TA_S, and no other power sources must be used. Only sensors that can access test signals and provide floating contacts are allowed to be connected.

Safe stop is divided into STOP 0, STOP 1, and STOP 2. Immediately cut off the drive and brake power supply for safety stop 0, KR C5 slim-2 uses STO signal, KR C5-2 uses SPO signal, and the brake power supply is cut off by SBC signal. Safety stop 1 is monitored by the safety controller, and the brake is applied and the drive is cut off no later than 2.3 seconds. In case of a fault, safety stop 0 is executed. Safe stop 2: Do not cut off the drive or apply the brake, maintain the braking slope deceleration along the path. The safety function complies with Category 3 and Performance Level d of EN ISO 13849-1, with a PFH value less than 1 × 10 ⁻⁷. The prerequisite is that safety related machinery and electromechanical components undergo functional testing at start-up and at least once every 12 months.

The operation modes include T1, T2, Automatic, and Automatic External. T1 is used for testing, programming, and teaching, with a maximum speed of 250 mm/s; T2 is used for high-speed testing and cannot be used for jogging; Automatic and Automatic External are used for program execution. The teaching pendant can be a smartPAD, smartPLUG with a tablet or laptop, or a laptop without a smartPLUG. When there is no smartPLUG, there is no emergency stop and enable device. The Motion enable external switch (non safety function) must be used, and an immediately accessible emergency stop must be configured near the laptop, with at least one additional emergency stop. The enable switch has three positions: not pressed, middle position, and fully pressed. Under T1/T2, only the middle position can move the axis; Release all intermediate position enable switches to trigger safety stop 1, and fully press one enable switch to trigger safety stop 1. Enable switches must not be fixed with tape and must undergo regular functional testing.

Installation, power on, and initial debugging

The KR C5 slim-2 must be installed in the sliding module of the KR C5 smallsizecab or compactcab. Before installation, it is necessary to confirm that there is no condensation or damage. Connect equipotential, motor cables, data cables, and power cables. The security interfaces XG11.1, XG11.3, and XG58 can only be plugged in and out when the controller is turned off, and live plugging may cause property damage. Power on sequence: Close the motor circuit breaker, close the cabinet door, release the emergency stop on the teaching pendant, and turn on the main switch. Control the PC startup sequence as recovery stick, external hard drive, internal hard drive; If an external hard drive is detected, the internal hard drive will be disabled; If no external hard drive is detected, it will not automatically switch to an internal hard drive. The robot controller can only operate together with the connected teaching pendant.

Functional testing must be performed: after all connected emergency stop devices are pressed, the user interface displays that the emergency stop has been triggered and does not display an error in the emergency stop device; After all enable switches are released in test mode, the robot stops without displaying any enable device errors; Press and hold the panic function of all enable switches for 3 seconds, and the robot will stop without any errors; Safety output shutdown capability test, after turning off and then turning on the controller, no safety output error is displayed. Braking test is used to check the braking torque of each axle, and whether it is executed and the frequency is determined by risk assessment. Security acceptance must be completed on a real system and cannot be replaced by simulation. The security configuration check must be performed after the security ID is changed, and all security configuration parameters must be checked, not just the modified parameters. Machine data inspection requires actual testing when there is an external axis, and the deviation must be less than 5%. In addition, the safety controller will automatically confirm connection errors on the safety input and output, and the output may switch from LOW to HIGH, causing peripheral devices to automatically restart, which must be prevented through appropriate measures.

Maintenance and module replacement

Maintenance must be carried out after the controller is turned off, the tag is locked, and the power cable is unplugged. After a power outage, there may be residual voltage of 60 to 800 V in the intermediate circuit for up to 5 minutes, and at least 5 minutes must be waited for. KSP、 Motor connectors and connected motor cables may remain energized. The homework must comply with ESD regulations. Maintenance table requirement: Conduct annual cyclic functional testing on operational safety and all emergency stop devices; Test all enable switches; Test external enabling devices; Test the Drives ready light before entering the danger zone each time; Clean the fan protective grille according to the degree of pollution; Replace the system board battery every 10 years. Check if the plug connection is secure and inspect all system components for wear or damage.

Module replacement includes: cleaning cooling fins, replacing system board batteries, replacing interface board fuses, replacing CSP cables, replacing IFBsafe, IFBsafext, IFBstd, NextGen system board, KAI board, connection board between power units and system boards, fans, power units, USS compact interface board, Ethernet expansion board. General steps: Turn off the main switch and prevent restart; Open the cabinet door; Disconnect the front plug; Unscrew 2 M5x20 screws and remove the guide rail; Remove the controller and be aware of the risk of compression of approximately 25 kg; Disconnect the rear plug; Open the housing cover and unscrew 8 M3x8 TORX screws; Replace components; Install the housing cover and tighten to a torque of 0.8 Nm; reinstall the controller and connect the plug; Close the cabinet door; Power on inspection. After replacing the system board battery, you need to plug in the USB keyboard, enter the BIOS to set the date and time, load the default values, and perform a functional test. The same amperage value must be used to replace the fuse. When replacing the NextGen system board, pay attention to the vertically installed connection board and do not tilt or damage it. When replacing the power unit, multiple boards and connection boards need to be removed in the correct order.

Common troubleshooting: Starting from power supply, safety chain, communication chain, and cooling chain

Unable to power on. Check XD1 power supply, line side fuse 3 × 10A to 3 × 16A slow melting, main switch, equipment switch, XD2 UPS power supply, and battery. If the control PC does not start, check the NextGen system board, internal fan, SSD, and recovery stick. When the startup sequence is abnormal, check if an external hard drive is inserted.

The safety stop cannot be reset. Check the emergency stop of the teaching pendant, external emergency stop, additional emergency stop, XG11.1 and XG58 dual channel status, operation safety signal, safety door, enable switch, and safety configuration. After triggering the safety stop 1, it is necessary to confirm that all axes have stopped and the brakes have been applied; After triggering the safety stop 0, it is necessary to check whether the driving and braking power supply has been cut off. If the security ID changes, the security configuration must be rechecked and security acceptance must be conducted.

The enable switch is invalid. Check the teaching pendant enable switch smartPLUG、 External enabling device, XG58 wiring, T1/T2 mode. The enable switch must be in the middle position to move; Releasing or fully pressing will trigger safety stop 1. The notebook mode without smartPLUG requires a Motion enable external switch, which is not a safety function.

The load voltage of USS 2 is abnormal. Check XG11.2 control, US2 compact interface board, XD56 load voltage output, XG57. x auxiliary contacts, XD6/XD6.1 power supply. US2 can be switched or disabled by external PLC, robot controller. If USS 2 cannot be turned off, it may cause unexpected actions of the actuator. It is necessary to regularly check the functionality of the USS 2, including initial startup, robot changes, security configuration changes, software updates, replacement of the USS interface board, and at least once a year.

Communication interruption. Check the KSI, KLI, KLI2, OSI, KEI, and KAI interfaces to confirm that KSI is not connected to the IT network, KLI is wired correctly, EtherCAT equipment is configured, cable length does not exceed 100 meters, and XG12 power supply is normal. If replacing the data cable, it is necessary to re master or perform a mastering test on all axes.

Cooling malfunction. Check the fan, protective grille, cooling fins, air inlet and outlet, ambient temperature, and installation spacing. Compressed air is prohibited during cleaning, water spraying is prohibited, solvent-free, water-soluble, non flammable, non corrosive cleaning agents are used, and they must not enter electrical components.

Battery malfunction. The system board battery is CR2032 and is replaced every 10 years. Set BIOS date and time after replacement. Battery failure may result in system time errors or configuration loss.

Recovery and mirroring. If the system cannot start, you can use the recovery USB to restore the image. After recovery, check the settings and perform functional testing. If replacing the SSD or system board, it is necessary to confirm that the operating system image and robot data are complete.