Application · Test rig
Passing Gigabit Ethernet through a slip ring spinning at 900 rpm
In brief
A customer asked for a slip ring assembly able to pass Gigabit Ethernet signals to a rotating part. The transfer was validated on an SR36M, a slip ring with 36 electrical connections, spun on a motor while a large file went from one computer to another through it.
- 111 MB/s
- file transfer speed through the slip ring
- 900 rpm
- rotation speed during the test
- 36
- electrical connections on the SR36M
Why send Ethernet to a rotating part
A slip ring passes power and signals to and from a rotating device, such as strain gage and thermocouple signals. It works like an electrical bearing. Some equipment on the rotating side now needs a network link as well.
The test setup
- 01
Cut the cable
A CAT 6 cable was cut in half.
- 02
Wire it through the rings
Each half was jumpered to the connections of the SR36M slip ring, to make the cable whole again through the rings.
- 03
Connect two computers
One end of the cable went to a laptop, the other to a PC.
- 04
Spin and transfer
The slip ring was spun at 900 rpm on a motor while a large file was transferred from one computer to the other.
SR series slip rings
The result
The file went through the slip ring with no signal drop-out and no error. The transfer ran at 111 MB/s and the received file was checked with an SHA-256 checksum.
What it shows
A standard instrumentation slip ring, the SR36M, carried a Gigabit Ethernet link at 900 rpm with no drop-out and no error. Another signal type can be validated the same way, on a bench, before the test.
Frequent questions
Can a slip ring carry Gigabit Ethernet?
Yes. In a validation test, a Michigan Scientific SR36M slip ring with 36 electrical connections passed a Gigabit Ethernet link while spinning at 900 rpm, with no signal drop-out and no error.
What data rate was reached through the slip ring?
The file transfer ran at 111 MB/s while the slip ring was spinning at 900 rpm. The received file was checked with an SHA-256 checksum.
How is an Ethernet cable wired through a slip ring?
In the test, a CAT 6 cable was cut in half and each half was jumpered to the connections of the slip ring, so that the cable was made whole again through the rings.
Was a special Ethernet slip ring used?
No. The test used an SR36M, a standard instrumentation slip ring with 36 connections, of the kind used for power, strain gage and thermocouple signals.
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