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Question:
GigaBlox Nano – 1 Inch GigaBit Ethernet Switch (SKU: BB-GGN-B-1)
In the Description tab it says cable lengths over 1m should proceed with caution. What is the limiting factor here and are we able to extend this easily? We would need to route a cable roughly 2m. Would a higher CAT ethernet cable mitigate some of this limitation?
Answer:
The cable length caution applies when using GigaBlox Nano in a transformerless Ethernet configuration, for example with the PicoConn-style direct wiring approach. In this setup, the Ethernet pairs are AC-coupled but not magnetically isolated, so the limiting factor is not simply Cat5e/Cat6 signal bandwidth. The main concern is DC/common-mode voltage imbalance between connected devices, plus reduced protection against ground offsets, EMC, and ESD compared with a standard magnetics-isolated Ethernet port. Our datasheet recommends keeping transformerless links to 1 m or less for this reason.
That said, a 2 m cable may work in a controlled system, especially if both devices share a clean common ground and are inside the same enclosure/platform. Using a higher-category Ethernet cable can help with signal integrity, shielding, and pair balance, but it does not remove the fundamental limitation, because the main issue is the lack of isolation rather than cable bandwidth.
The clean way to extend this is to use magnetics/isolation. If you use GigaBlox Nano with the RJConn daughterboard, or a custom daughterboard that includes compliant Ethernet magnetics, then you can achieve 30 meters or more.