RKB0021 by Bosch Rexroth Indramat

The RKB0021 is a control cable produced by Bosch Rexroth Indramat within the RKB Control Cables series. It is supplied as a finished assembly for Ethernet-based motion networks, linking drives and PLCs that communicate over Sercos III on a real-time bus. In automated equipment, it carries cyclic communication between networked components so coordinated axes can exchange timing-sensitive control data without added field assembly. Molded connectors and finished terminations reduce installation work while supporting deterministic signaling required by synchronized industrial automation nodes.

This basic model uses twisted-pair conductors for 100 Mb/s Ethernet traffic. The internal wiring uses a 4-core layout for data transmission and timing. The assembly is rated for 3,000,000 flex cycles, allowing repeated movement in drag-chain applications where continuous cable travel is expected. During motion, the cable requires a minimum bend radius of 7.5 × D to limit mechanical stress on the conductors and jacket. Service temperature may reach 70 °C in powered operation, which supports placement near warm drive components or cabinet exhaust paths.

The cable remains suitable for ambient conditions down to -40 °C, and storage is permitted to -50 °C when the assembly is not in service. Each end uses a straight RJ45 connector that mates with standard drive, PLC, or switch receptacles in industrial Ethernet networks. Because the cable is delivered as a finished assembly, no field termination is required, which helps preserve line consistency where impedance control matters. Finished terminations also reduce wiring errors that can interfere with high-speed communication. The cable can be routed through machine sections that alternate between motion and fixed panel runs, provided the appropriate bend guidance is observed for each section.