What it is and what it connects
The Siemens 6GT2891-4MH50 is a pre-assembled IO-Link connecting cable from the SIMATIC RF family, purpose-built to link an IO-Link device (like an RFID reader) to an IO-Link master. Both ends terminate in M12 4-pin straight connectors — male on one side, female on the other — so it plugs directly between the sensor and the master without field wiring. The cable runs 5 m fixed length, unshielded, with three cores (brown, white, blue, black wire insulation) in a black PVC jacket. The 30 V maximum rating matches the standard IO-Link voltage range, so it handles the 24 V DC supply and data line common in IO-Link v1.1 systems.
Key ratings and what they mean for fit
The 30 V maximum is the voltage ceiling for the cable assembly — IO-Link masters typically output 24 V DC, so this is comfortably above the working voltage. The 5 m length is the fixed pre-assembled run; if your panel layout needs a longer or shorter drop, this exact order code won't stretch or trim. The jacket carries flame-resistant ratings per AWM STYLE 21317: VW-1 for USA applications and FT-1 for Canada, both at 80 °C. That means the cable passes vertical flame testing for use inside control cabinets or cable trays where flammability compliance matters. It is not halogen-free, so if your spec requires zero-halogen for smoke density in occupied spaces, this isn't the cable for that job. Minimum bend radius with a single bend is 34.4 mm; with multiple bends it's 64.5 mm. That's tight enough for routing inside a junction box or along a DIN-rail channel, but the symmetrical outer diameter tolerance of 0.15 mm means the jacket thickness is consistent — no bulges that snag during pull-through.
Where it goes in the system
This cable sits between an IO-Link master (typically a SIMATIC RF120C or similar) and an IO-Link-capable reader or sensor. The M12 4-pin connectors are standard for IO-Link — pin 1 is 24 V, pin 3 is 0 V, pin 4 is the data line (C/Q). The straight form factor means it works best where both ports face the same direction; if you need a right-angle exit to save space, you'd look for a different cable variant. The cable is designated LiY-11Y 4xAWG 22/19, which is a PVC-insulated, unshielded data cable with 22 AWG stranded conductors. Loop resistance per meter is 108 mΩ/m maximum, so at 5 m the total loop resistance is about 0.54 Ω — negligible for IO-Link's 24 V supply, but worth noting if you're daisy-chaining power through multiple cables.