Tuesday 9 August 2022

An Ethernet Moment

Another Australia Post delivery this morning resulted in all but the last few components of the yacht navigation system being received.

I must be getting more patient in my latter years as I’m not rushing to assemble everything and then having to repeat work because it’s wrong!  It’s quite likely I won’t start assembling the components until after my return from inspecting the yacht in New Zealand.  I need to know the exact location of the case to ensure I have all the external plugs, switches, display, etc where they will be accessible.

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The brain of the system will be the Single Board Computer (SBC), a Raspberry Pi.  Not the one in the above photo.  That’s a model 2 and has insufficient computing power.  I need a model 4 and there is currently a world-wide shortage of them.  However the model 2 is exactly the same size as the model 4 which is helpful when planning the component layout.

The system will be access wirelessly but as the Raspberry Pi has an ethernet port I thought it might be useful to extend the port on the Raspberry Pi to the case which would then provide a network cable capacity.  It proved very difficult to buy one ethernet wall socket and I ended up having to purchase six for $1.75.  Maybe I can sell the five surplus and make a profit Smile

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I thought I was rather clever buying a socket where the cables don’t need to be soldered.  My eyesight is getting too poor for fine soldering and my hands also shake… Damned curse of old age!

The ethernet extension consists of a short length of old ethernet cable with a moulded plug.   The outer plastic casing was stripped from the cable to make it easier to position inside the case.

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It was at this point I realised I might have an issue.  The colours of the wires on the old cable didn’t match the colour coding on the new socket?  With a magnifying glass I could see there was a code on the blue plug.

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T568A

The code on the socket was T568A/B.

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Then I realised the socket had the colour coding for T568 A and T568B in two rows.

Eventually I managed to place the eight wires in the correct grooves on the socket and close the lid crimping them in place.  However I wasn’t convinced I’d correctly installed the wires so I plugged the cable into the Raspberry Pi and connected the ethernet cable from the router to the new socket to test my wiring.

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It works!

6 comments :

Don said...

Don't let a data cabling guru see that cable as the performance will be reduced. Another option would have been to use a bulkhead joiner with a short ultra slim patchcord to connect to the pi.

Tom and Jan said...

Yes... I probably am doing myself a disservice showing my dodgy wiring!

Dave said...

Depending on how "noisy" an environment its going into i'd go for shielded cable or maybe even a shielded case

Pip and Mick said...

We always used 568B as do most people in the UK. It doesn't really matter as long it is the same at both ends. Standard cat 5 cable would be better than the loose pairs that you have. Inside the cable the pairs are twisted around each other which helps prevent interference. But I suspect over the short distance you have there you'll be ok.

Mick

Tom and Jan said...

This is a low cost option for a low cost yacht. I can see that not having the weires twisted increases the possibility of interference and I will twist the wires together when they go into the case. Does the plastic sleeve actually reduce interference? This is for a yacht at sea and I ask myself what will be the sources of electromagnetic interference. The bilge pump or perhaps the motor alternator? I suspect the grandson will use the WLAN rather than ethernet.

Pip and Mick said...

Does the plastic sleeve actually reduce interference?

No. It's the pairs twisted together at the correct rate of twist that does it.
I suspect you'll be fine.

Mick