The Siemens 6GT2891-2UH30 is a pre-assembled RS-232 communication cable for the SIMATIC RF1000 family, specifically linking an RF1040R or RF1070R reader to a controller with a screw-terminal RS-232 interface — for example, an ET 200SP module. It carries a 300 V maximum rating and is UL AWM 2464/2517 listed on the cable section without the plug, so it's accepted in North American panels that require UL-recognized wiring. The cable is 3 m long, 4-core, with a braided shield of tin-plated copper — that shield is what keeps the RS-232 signal clean in a noisy cabinet with drives or contactors nearby.
Construction and environmental resistance
The cable sheath is black PVC, flame-resistant per IEC 60332-1-2, halogen-free no, silicon-free yes. It resists water and mineral oil, and is rated for UV radiation exposure — useful if the reader end lives in a washdown zone or near a window. Installation temperature matches the operating range, so don't pull it in freezing conditions. Minimum bend radius is 69 mm for both single and multiple bends — that's about 2.7 inches, tight enough for most cable ducts but worth checking if you're routing through a crowded trough.
The cable designation is LiYCY 4x AWG26 — that's a standard shielded data cable, so if you ever need a custom length, the raw cable is available, but the pre-assembled version with the PicoBlade 51021 5-pole connector on one end and open ends on the other is what this order code delivers.
The 300 V rating is the cable's maximum working voltage between conductors — well above the typical RS-232 signal levels (±12 V or so), so the margin is generous. What matters more is the UL listing: if your panel requires UL-recognized wiring, this cable qualifies on the cable portion (the plug end is not separately UL-listed, per the spec). Loop resistance is 130 mΩ/m maximum — for a 3 m cable that's about 0.39 Ω per conductor, negligible for RS-232 at its standard baud rates. The shield's tin-plated copper braid gives good coverage against EMI from nearby VFDs or switching power supplies.