KUKA KRC2 Drive Bus Error on All Axes — It’s the Shared Ring, Not the Motors
A KUKA KRC2 drive-bus fault on every axis at once points to the shared MFC-KSP-KSD ring. Isolate the Interbus ring node-by-node instead of swapping the drive stack.
Drive bus error on all axes — it’s the shared ring, not the motors
“Antriebsbusstörung” / drive bus + servo-parameter + power-module + DSE faults arriving together.
The drive-bus Interbus ring (redrawn)
Read the message first
245 Servo bus disturbance→ defective bus cable / module / driver → reseat & test the ring.28 / 29 Drive bus DSE participant→ config ≠ hardware → coordinate Interbus config (after adding/removing a KSD).268 / 269 DSE→ “exchange DSE or MFC” / “check DSE, check MFC” → the master end.- KSD panel
SYNCHRONISATION ERROR→ manual remedy: “Check Interbus cable between DSE, KPS and KSD”.
Isolate, don’t swap the stack
- Reseat & clean every white Interbus connector along the ring.
- Segment test: disconnect KPS→KSD1, add one KSD at a time, reboot between.
- Wiggle test the suspect cable + both connectors.
- Aged bus lines are a common root cause — replace worn cabling.
- Don’t replace motors / RDC / a single KSD before the bus is proven clean.
Diagnostic path
Sources: KUKA KRC2 ed05 Operating Instructions — p.14/15/33/100/116; KUKA KSS System Messages — p.11–12/38/39/47; KUKA Fault Listing Manual — p.25 (245/246).
Drive bus error on all axes at once — it’s the shared ring, not the motors
A fault that hits every axis simultaneously points to the common drive bus (Interbus), not to six individual drives failing together.
The question
When a whole cluster of drive faults arrives together and covers every axis, the useful question is not “which motor failed” but “which part of the shared drive-communication path is down, and how do I isolate it without swapping the whole drive stack.”
Short answer
What the messages mean (verified)
The message text (and its <DSE number>) tells you which layer is complaining. Two manuals corroborate:
| Message | Cause (manual) | Points at |
|---|---|---|
245 SERVO BUS DISTURBANCE DSE |
“Defective bus cable. Defective bus module. Defective bus driver.” | The bus itself — cable / node hardware |
246 … no buffering |
Buffering is activated via the servo bus on the KPS; if communication with the KPS is faulty, switch-off is immediate | KPS600 comms on the bus |
28 / 29 Drive bus DSE participant … |
“Interbus configuration and physical structure do not match” → coordinate Interbus configuration and hardware | A node missing / added / mis-configured |
267 Watchdog power module |
Power-module watchdog dropped out (triggered by the DSE) | KPS / DSE supervision |
268 Memory test error DSE |
DP-RAM memory test on the DSE was incorrect → exchange DSE or MFC | DSE / MFC hardware |
269 DSE not available |
MFC “DSE present” bit not set although axes are connected → check DSE, check MFC | DSE / MFC seating or fault |
| 241 / 243 servo params / DSE software | Servo file / DSE software does not fit the firmware or hardware | Config after a firmware/board change |
Sources: KUKA KSS System Messages — 27–30 drive bus DSE (p.11–12), 237 common drives error (p.38), 239–242 servo parameters (p.39), 267–269 (p.47); Fault Listing Manual — 245/246 servo bus disturbance (p.25). The KSD front-panel SYNCHRONISATION ERROR DRIVE MODULE remedy is literally “Check Interbus cable between DSE, KPS and KSD” (Operating Instructions, p.116).
Where it sits: the drive-bus Interbus ring
DSE-IBS (MFC3) → KPS600 → KSD1 … KSD6 → back to DSE — a series loop
Topology redrawn from the KRC2 ed05 architecture: ST3 = “drive bus to KPS600” (Operating Instructions, p.14); KPS600 “via the drive bus … communication is monitored by a watchdog … short-circuit braking”, “Interface to DSE-IBS and servo drive modules”, “Interbus monitoring” (p.33); KSD = KUKA Servo Drive, 6 robot + 2 optional external (p.33/37). Original diagram, not a manual reproduction.
Step 1 — read the exact message before you touch anything
The three families above call for different actions, so pin the wording first:
- Bus disturbance (245/246, or a KSD “synchronisation error”) → the physical bus: cable / connector / a node. Go to Step 2.
- Participant mismatch (28/29 “Interbus configuration and physical structure do not match”) → the configuration no longer matches the hardware. Expected after adding/removing a KSD or an external axis; here the remedy is to coordinate the Interbus configuration with the actual hardware, not to swap parts.
- DSE / MFC hardware (268 “exchange DSE or MFC”, 269 “check DSE, check MFC”) → the master end of the bus.
Step 2 — isolate the ring node-by-node (don’t swap the stack)
Switch off the controller and secure it; then wait 5 minutes for the intermediate circuit to discharge. Voltages up to 600 V can remain in the KPS, the KSDs and the intermediate-circuit cables after switch-off (Operating Instructions, §10.17). Observe ESD precautions. Qualified personnel only.
- Inspect and reseat every Interbus link along
DSE → KPS600 → KSD1 → … → KSD6and the return. Look for a loose or oxidised connector; clean the contacts. The manual’s own KSD remedy is “Check Interbus cable between DSE, KPS and KSD” (p.116). - Segment test: disconnect the KPS600→KSD1 link, then reconnect the KSDs one at a time, rebooting between steps, until the fault reappears — the segment you just added carries the fault (cable or the node at its far end).
- Wiggle test the suspect cable and both its connectors while watching the message — catches an intermittent break that a static check misses.
- Swap-to-confirm a node: only after the cabling is proven, move a suspect KSD/cable to a known-good position; if the fault follows the part, replace that part. Aged bus lines are a common root cause — replacing the bus cabling is a reasonable step when connectors show wear.
- If everything downstream is clean and 268/269 persist, the fault is at the master: check the DSE-IBS-C33 seating on the MFC3 (its LED should flash after run-up, p.100), then the MFC3.
Could it be a single drive, motor or the RDC?
Unlikely, given the pattern. A fault confined to one motor or its feedback shows up as a single-axis symptom — a resolver/encoder chain fault (e.g. code 102/105, “error in data transmission between DSE and RDC”) names one axis and lives on the RDC/resolver side, not the drive bus. Your cluster is all axes at once, which is the signature of the shared Interbus ring or its master. Check the single-drive hypotheses only after the bus is proven clean, or if the messages start naming one specific axis.
Open points / to verify
- Naming: on the KRC2 the drive power supply is the KPS600 (the term “KSP” belongs to the later KR C4). The corpus describes the KRC2 KPS600; confirm which module your cabinet actually carries.
- KSS build: exact message numbers/text vary slightly by KSS 5.x build — rely on the message text and the
<DSE number>, not only the number. - Cable part / values: the corpus gives the topology and the “check the cable” remedy but not the Interbus cable part numbers or expected continuity values — those come from the spare-parts catalog (on the CD supplied with the controller), a declared gap.
Sources: KUKA KRC2 ed05 Operating Instructions — ST3 drive bus (p.14), slots MFC3/DSE-IBS (p.15), KPS600 & KSD architecture (p.33), KPS600 exchange & 600 V caution (p.100), KSD error display / Interbus remedy (p.116); KUKA KSS System Messages — 27–30 (p.11–12), 237 (p.38), 239–242 (p.39), 267–269 (p.47); KUKA Fault Listing Manual — 245/246 servo bus disturbance (p.25).
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