HS-Link cable assemblies are the physical interconnects used in KUKA robot axis communication — connecting KRC4 and KRC5 controllers to robot joint groups via plastic optical fibre (POF) or shielded twisted-pair conductors. Custom hs-link cable assemblies must meet KUKA’s strict transmission timing, bend-radius, and flex-cycle requirements; a failed or degraded assembly triggers axis faults, E-stop events, or positioning errors that halt production. Nexharn Connectivity manufactures custom hs-link cable assemblies to KUKA’s dimensional and electrical specifications, for OEM integrators and end-user replacement programmes worldwide.
This guide covers hs-link cable assemblies technical specifications, pin layout, data rate ratings, applications across robotics and telecom, a comparison with MRJ21 and M12 connectors, and custom manufacturing options including MOQ and lead times.
For a broader product overview, see our MRJ21 and HS-Link cable assembly landing page and our industrial cable assemblies product range.
What Are HS-Link Cable Assemblies
HS-Link (High-Speed Link) is a proprietary KUKA Robotics communication protocol transmitting real-time servo data between the robot controller (KRC4 or KRC5) and axis groups or external axes. The HS-Link bus carries synchronised multi-axis servo position, velocity, and status data at 10 Mbit/s with cycle time below 1 ms — parameters that demand tight optical budget control across the cable run.
Unlike generic industrial Ethernet cables, HS-Link cable assemblies are terminated with KUKA-proprietary push-pull POF connectors and validated to KUKA’s specific bend radius, flex-cycle, and optical attenuation requirements. For system integrators commissioning KUKA cells and maintenance engineers managing ageing installations, specifying correctly manufactured HS-Link cable assemblies is a system-critical decision.
Technical Specifications: Pin Layout, Ratings and Data Rates
HS-Link cable assemblies span two physical-layer technologies depending on KUKA controller generation and installation requirements.
Plastic Optical Fibre (POF) Variant — KRC4 / KRC5 Standard
- Connector type: KUKA-proprietary push-pull POF connectors (not standard ST or SC)
- Fibre diameter: 1 mm PMMA step-index POF (e.g., Mitsubishi Eska SH-4001 or equivalent)
- Wavelength / LED source: 660 nm red LED
- Attenuation budget: ≤ 2.5 dB over the full cable run
- Minimum bend radius (dynamic): 25 mm — verified for cable-carrier and torsion routing
- Operating temperature: −30 °C to +85 °C (static); −5 °C to +70 °C (dynamic bending)
- Data rate: 10 Mbit/s serial cyclic; cycle time < 1 ms
- Jacket material: PUR (polyurethane) standard; PVC available for fixed-route installations
- Ingress protection (assembled): IP40 standard; IP67 optional with sealed boot
Electrical STP Variant — External Axis / Compact Controllers
- Conductors: 2 × shielded twisted pairs (STP), 0.25 mm² stranded copper
- Characteristic impedance: 100 Ω ± 15 Ω
- Connector: M12 D-coded (IEC 61076-2-101) or KUKA circular proprietary
- Shielding: Aluminium/foil + tinned-copper braid, ≥ 90% optical coverage
- Voltage rating: 30 V DC (signal only)
- Minimum bending cycles: 5,000,000 (cable-carrier / torsion-rated)
- Ingress protection (assembled): IP67
Applications for HS-Link Cable Assemblies
Robotics and Industrial Automation
The primary application of HS-Link cable assemblies is KUKA robot axis communication — specifically KRC4 (2010–present) and KRC5 (2020–present) controllers. Failure or noise on the HS-Link bus manifests as KUKA fault code KSS 00128 (fibre break) or axis following errors. Custom-length HS-Link cable assemblies are essential for non-standard reach installations or when the control cabinet is relocated beyond the standard 7 m tether. Our industrial HS-Link and MRJ21 buyer’s guide covers these applications in greater depth.
Telecom and Networking Infrastructure
POF-based HS-Link technology is reused in industrial Ethernet media converters and short-reach board-to-board links inside telecoms equipment. The 660 nm POF segment provides galvanic isolation while maintaining data integrity in high-density 19-inch rack environments. For standard compliance reference, the IEC 60793-2-40 standard governs multimode optical fibre categories relevant to POF link budgets in these installations.
Data Centre and Server Manufacturing
Server OEMs use HS-Link-compatible POF assemblies for intra-chassis communication. POF’s inherent galvanic isolation prevents noise coupling between power-supply modules and management controllers. Short runs of 0.5–3 m are typical inside server enclosures where POF weight and flexibility advantages over multimode fibre are commercially significant.
HS-Link Cable Assemblies vs MRJ21 vs Other High-Density Connectors
Procurement engineers often compare HS-Link cable assemblies with MRJ21 and other connector systems when sourcing industrial connectivity solutions. The table below clarifies the correct application for each technology.
| Feature | HS-Link (POF) | MRJ21 (Electrical) | M12 D-coded Cat6 | SFP+ DAC |
|---|---|---|---|---|
| Physical medium | 1 mm PMMA POF | 24 × UTP copper pairs | 4-pair STP copper | Twin-ax copper |
| Data rate | 10 Mbit/s (serial) | Up to 1 Gbit/s per pair | 1 Gbit/s | 10–25 Gbit/s |
| Max segment length | ~30 m (attenuation limited) | 100 m (Cat6 / Cat6A) | 100 m | 1–5 m |
| EMI immunity | Excellent (optical isolation) | Good (foil + braid) | Good | Moderate |
| Galvanic isolation | Yes — inherent | No | No | No |
| IP rating (assembled) | IP40–IP67 | IP20–IP40 | IP67 | IP20 |
| Primary use case | KUKA robot axis control | Data centre ToR fan-out | Industrial Ethernet to sensors | Server / switch stacking |
| Custom lengths | Yes — 0.5 to 30 m | Yes — 0.3 to 100 m | Yes | Limited (passive) |
For 24-port data-centre fan-out cabling, see our MRJ21 cable assemblies page.
Custom HS-Link Cable Assemblies: Options, MOQ & Lead Times
Nexharn Connectivity manufactures custom HS-Link cable assemblies to production-grade specifications:
- Cable lengths: 0.5 m – 30 m (POF); 0.5 m – 20 m (STP). Custom lengths in 0.1 m increments.
- Connector termination: KUKA-compatible POF push-pull, M12 D-coded IP67, or bare-end for in-cabinet self-termination
- Jacket options: PUR flex/torsion (standard), PVC fixed-installation, TPE low-temperature (−40 °C rated)
- Marking: Customer part number + manufacture date code printed every 500 mm
- Testing: 100% optical power budget measurement (POF) / 100% continuity, NEXT, insulation resistance (STP)
- Prototype / sample: 1–5 pcs, 5–10 business days. Tooling cost waived for follow-on orders > 200 pcs.
- Production MOQ: 10 pcs per part number
- Standard lead time: 15–20 business days after golden-sample approval
- Rush lead time: 7–10 business days (surcharge applies)
- Payment terms: T/T 30% deposit + 70% before shipment; LC at sight for orders > USD 20,000
To start your custom HS-Link cable assembly project, submit an RFQ with your KUKA controller model, cable length, connector termination, and quantity.
FAQ
What is the difference between HS-Link and a standard POF cable?
HS-Link is KUKA’s application-layer protocol; the physical medium is 1 mm PMMA plastic optical fibre. HS-Link cable assemblies are terminated with KUKA-proprietary push-pull connectors and tested to KUKA’s optical budget, bend, and flex-cycle requirements. A generic POF cable with F-SMA connectors will not interface correctly with KRC4/KRC5 HS-Link ports.
Can I use longer HS-Link cable assemblies than the standard 7 m?
Yes, up to approximately 30 m for POF variants, subject to an attenuation budget of 2.5 dB. Extended-length hs-link cable assemblies require higher-quality low-loss POF fibre and precision connector polishing. Nexharn supplies extended-length cables with a full optical power-budget test report confirming KUKA receive-sensitivity compliance.
What causes HS-Link cable assembly failures in robot installations?
The most common causes are: (1) bend radius below 25 mm causing POF fibre fracture; (2) connector face contamination; (3) UV degradation; (4) crush damage. PUR jacket and verified minimum bend radius maximise service life of hs-link cable assemblies.
Do you supply HS-Link cable assemblies for both KUKA KRC4 and KRC5?
Yes. KRC5 uses a revised connector housing but the same 1 mm POF medium. Please specify your controller generation and robot model when submitting your RFQ for hs-link cable assemblies so we can confirm the correct connector termination.
What is the minimum order quantity for HS-Link cable assemblies?
Our production MOQ for hs-link cable assemblies is 10 pcs per part number. For urgent single-piece replacement requirements, we can supply from finished-goods stock where available. Contact us with your KUKA robot model and cable part number.
Can you provide UL-listed HS-Link cable assemblies?
Yes. PUR and PVC jacket variants for hs-link cable assemblies are available with UL 20549 / UL 21098 recognised conductors. CE, RoHS 2, and REACH SVHC compliance documentation is supplied with every production lot.