KUKA KR C5 Controller Assembly and Troubleshooting

KUKA KR C5 Controller Assembly and Troubleshooting

In the field application of industrial robot controllers, the KR C5 Controller is no longer a single "control cabinet" concept, but a modular platform composed of control units, power units, safety logic, interface boards, cooling systems, and UPS. It is designed for KUKA industrial robots, supporting up to 7 servo axes, with a protection level of IP20 and a weight of approximately 25 kg. It is available in KR C5 S6/S7, M6/M7, L6/L7 and other specifications, and comes in both AC and DC versions. For engineers in the search solution phase, the most important concerns are how to identify critical components, configure safety chains, wire connections, power on, replace modules, and where to start checking after an alarm. This article revolves around these practical issues.

System architecture: First distinguish between control unit and power unit

The KR C5 Controller consists of a control unit and a power unit. The control unit, also known as the control box, contains mini CSP, SSD hard drive, button battery, SYBperf system board, IFBstd standard interface board, IFBsafe safety interface board, IFBsafext safety expansion interface board, and internal fan. Mini CSP is a status display component that provides feedback on operating mode, operating status, errors, and sleep status through LEDs and soft power buttons. The system board is responsible for graphical interface, program creation and modification, path planning, sequence control, driver circuit control, monitoring, and communication of safety devices. The interface board provides non secure digital I/O, secure I/O, and secure extended I/O required for SafeOperation.

The power unit, also known as the drive box, includes an external fan, a heat sink, and a KSP-600 drive controller. The internal components consist of FCU-600 and SCU-7-1L. It is responsible for generating intermediate circuit voltage and system voltage, controlling motors, controlling brakes, and checking intermediate circuit voltage in braking mode. It should be noted that the power unit is not allowed to be opened arbitrarily, otherwise it may cause serious injury or property damage.

KR C5 also supports the Customer Kinematics variant, which can use KUKA motors to control non KUKA industrial robots. In terms of cabinets, KR C5 dualcab provides 2 rack units, triple cab provides 3, and quad cab provides 4. DualCab SR is designed for single robot applications, with a maximum of one robot controller and one device board. The control unit and power unit are connected through a vertically installed connection board, which must be used with extra caution when replacing system boards or power unit related components.

Security Chain: STOP 0, STOP 1, STOP 2 and Security Interface

The safety functions of KR C5 comply with Category 3 and Performance Level d of EN ISO 13849-1, and the PFH value is usually less than 1 × 10 ⁻⁷. The premise is that each emergency stop device should be pressed at least once every 12 months, each enabling device should be checked at least once every 12 months, and the USS 2 peripheral contactor should also be tested regularly.

Safe stop is divided into STOP 0, STOP 1, and STOP 2. STOP 0: The safety controller immediately cuts off the driving and braking power supply; STOP 1 is executed by the non safety part for braking, monitored by the safety controller. At T1, all axes come to a standstill or cut off the braking power supply no later than 680 ms, followed by a delay of 200 ms to cut off the drive. At T2/OUT/OUT EXT, the drive is cut off after 1.5 seconds by default; After STOP 2 braking, the driver remains activated, the brake is released, and it switches to safe stationary monitoring. Safety stop 1 DRS is used for safety options with BBRA, and after braking, the brake power is cut off according to the configured time plus 500 ms oscillation time.

The safety interface is a key point for on-site wiring. XG11.1 provides 2 safety inputs and 1 safety output for external emergency stop and operational safety. XG11.3 provides more secure inputs and outputs, including operation safety confirmation, peripheral enablement, safe operation stop, safe stop 1/2, safe stop 2, etc. XG13.1 and XG13.2 are used for options such as SafeRangeMonitoring, SafeOperation, SafeSingleBrake, etc. XG58 is used for external enable switches and additional emergency stops. When not connected, it needs to be short circuited according to the instructions. The Ethernet safety interface supports PROFIsafe, CIP Safety, and FSoE, with input bytes including external emergency stop, operational safety, operational safety confirmation, and safety stop 1/2 US2、 Signal to stop safe operation.

The external enable switch has three positions: not pressed, middle position, and fully pressed. Only the middle position can move the axis; Releasing or fully pressing will trigger Safety Stop 2 or Safety Stop 1. The enable switch must not be fixed with tape, otherwise it will lose its safety significance. In T1 mode, the default limit for axis specific speed is 30 °/s for the rotating axis, 250 mm/s for the linear axis, and 250 mm/s for the Cartesian speed. Exceeding the limit triggers a safety stop of 0.

Interface layout: front door, connection panel, and cable routing

The front view interfaces of KR C5 include: XG19.1 for smartPAD, XFUSB1/2 for USB, XF1 to XF8 for Ethernet and EtherCAT, XGDP for DisplayPort, XGSD for microSD card, IFBstd providing XD12/XD12.1 24V power supply and XG12 digital I/O, IFBsafext providing XG13.1/13.2, IFBsafext providing XG11.3, in addition to XG11.2 controlling US2, XG42 reference switch, XG58 safety interface, XG11.1 safety input-output, XF21.1 external shaft drive box, XF21 RDC, XD55 power supply, XG33 fast measurement and Drives ready light, XD20.1 to XD20.7 motor interface, XD10.1 to XD10.3 brake interface.

The rear view includes XD1 power connection, XD3 braking resistor, XD2 UPS 24V power supply, and battery testing synchronization. External axes can only be connected to specified interfaces: drive box XD20.1/XD10.1, XD20.2/XD10.2, XD20.3/XD10.3, or robot controller XD20.7/XD10.3. The motor cable must be laid separately from the data cable, with a fixed installation bending radius of 3 to 5 times the cable diameter, and a drag chain installation radius of 7 to 10 times. After replacing the data cable, it is necessary to perform mastering again or perform mastering tests on all axes.

XG12 provides 16 non safety inputs and 16 non safety outputs, which can be configured in high side or low side mode. Power is provided through XD12. XG33 provides 4 fast measurement inputs and Drives ready light outputs, with sensor power provided internally. XG42 is used as a reference switch and is a necessary interface for mastering testing. XD1 is available in AC versions as PE, L1, L2, L3, and in DC versions as PE, L+IN, L-IN, L+OUT, L-OUT. XD2 is used for UPS, with a maximum of 6.5 A for the first 60 seconds after power failure, and a maximum of 4 A until complete shutdown. Without UPS, the controller should not operate, otherwise data loss may occur.

Installation and initial power on: Lock and connect

The KR C5 controller must be installed in the KR C5 dual cab, triple cab, or quad cab. Before installation, it is necessary to confirm the AC/DC version. The coding pin can prevent mixing: the AC version has 2 pins with a diameter of 5mm, and the DC version has 1 pin with a diameter of 7mm. Push the controller into the cabinet and lock it. The locking action will connect the power supply, braking resistor, and UPS. The grounding conductor must be connected, and the equipotential connection should be carried out according to the cabinet instructions.

The security interfaces XG11.1, XG11.3, and XG58 must be plugged in and out when the controller is powered off. The configuration should comply with the system and security concepts. SmartPAD is connected to XG19.1, and the cable can be led out from the cabinet. The shielding layer is inserted into the shielding clip and stress relief is done with zip ties. The power on sequence is: close the motor circuit breaker, close the cabinet door, release the smartPAD emergency stop, 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.

Before the first start-up, check for condensation, damage, plug locking, and cable twisting. Functional testing includes: local emergency stop, external emergency stop, enabling device, operational safety, USS 2, Drives ready light. The US2 function must be checked after initial startup, robot changes, safety configuration changes, software updates, and replacement of load voltage contactors. The Drives ready light must be tested before entering the danger zone: press and hold the enable switch at T1, and the light should turn on; Press to the panic position, the light should turn off.

Maintenance and module replacement: Power off and wait for 5 minutes

The maintenance of KR C5 can only be carried out after the controller is powered off and locked with a tag. 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; Check the output of IFBsafe and IFBsafeext relays; Test US1/US2; Test all enable switches; Test external enabling devices; Test the Drives ready light before entering the danger zone each time; Clean the fan and heat sink according to the degree of pollution; Replace the system board battery every 10 years.

Module replacement includes: cleaning heat sinks, replacing SSD hard drives, replacing system board batteries, replacing interface board fuses, replacing IFBsafe, IFBsafext, IFBstd, system board, internal SSD, connection board between system board and power unit, KSP-STA interface card, control unit fan, power unit fan module, and transfer nameplate. The general steps are: turn off the main switch, open the front door, turn off the motor circuit breaker, unplug the front plug, pull out the pin, rotate the locking lever, and remove the controller. The controller weighs approximately 25 kg and poses a risk of compression. Protective gloves and safety shoes must be worn and slowly pulled out to prevent connector breakage or cable clamping.

After replacing the system board battery, plug in the USB keyboard, enter the BIOS to set the date and time, load the default values, and perform a functional test. After replacing the SSD, check the settings and perform a functional test. After replacing IFBsafe or IFBsafext, check whether the CSP LED is lit and whether the startup is normal. When replacing the internal SSD, one M3x2.5 cross screw needs to be unscrewed. When replacing the connection board, the system board should be removed first, and then the connection board should be pulled out vertically. Be careful not to tilt it during installation. When replacing KSP-STA, it is necessary to remove 5 M3x8 TORX screws and pay attention to the vertical connection plate.

Common troubleshooting: Starting with KSP alarm and CSP LED

KSP warning messages are the focus of investigation. 26103 internal error: reinitialize the driver bus, Power Off/On。 26104 IxT overload: When starting, the program load is too high. During operation, check the mechanical, temperature, and current trajectories, reduce the program speed, and check the CBS pressure and gearbox. 26105 Grounding Fault: Check the motor cable and motor. 26106 Overcurrent: Check the current trajectory, motor, and motor cable. 26107 Intermediate circuit overvoltage: Check the trajectory of the intermediate circuit, main power supply, and braking resistor to reduce the braking load. 26108 Intermediate circuit undervoltage: Check the trajectory of the intermediate circuit and the main power supply. 26112 radiator overheating: Check the fan, ambient temperature, program load, cooling circuit cleanliness, installation position, and ventilation gap. 26113 motor phase loss: Check the motor cable and motor. 26114 communication error: reinitialize the driver bus, check the EtherCAT cable and stack. 26118 Power phase loss: Check the power cord. 26119 power failure: Check the power cord and fuse. 26122 brake resistor fault: Check the brake resistor. 26123 Braking resistor overload: Reduce frequent braking overload and check the braking resistor. 26131 Intermediate circuit charging failure: Check the intermediate circuit cable, main power supply, and system impedance. 26133 brake fault: Check the motor/brake, brake cable/motor cable.

CSP LED is also an important clue. LED1 white indicates operating mode, LED2 green indicates operating status, LED3 red indicates error, and LED4 white indicates sleep/soft power. All off indicates that the controller is turned off; Irregular flashing of LED4 indicates sleep mode; LED4 flashing slowly indicates Bus Power Off. When LED1 to LED4 are all on during startup, it indicates LED testing, and then turning off indicates that BIOS POST is still running; LED2 slow flashing indicates that BIOS is OK and startup has started; LED2 lights up to indicate startup completion. When running, LED2 lights up to indicate T1/T2, and LED1 and LED2 lights up to indicate automatic mode. LED3 flash indicates PROFINET ping, slow flash indicates maintenance mode.

Regarding startup errors: LED2 flashing and LED3 lit up indicate a BIOS error. You can replace the SSD or check the USB; If LED2 flashes slowly and LED3 lights up, it indicates that PMS startup has timed out and the mirror needs to be reloaded; LED2 and LED3 flash rapidly, indicating a software startup error and the need to reload the image; During operation, both LED2 and LED3 are lit, indicating a fatal error. Please check the smartPAD error message. The recovery image can be created or restored using KUKA. Recovery USB V4 or higher, in conjunction with Windows 10 64 bit PC, following the CSP status prompt to create or restore C and D drive images. If the system board LED lights up red, turn off the controller, unplug the power cord, and contact KUKA customer service.