[DG] [DG11] ST NG Backbone length versus Spur length

[[email protected]]

Hi There,
I have a combined ST1 and STNG Network (see thread [CA11] ST60+, seatalk1, seatalk NG, ray55e, A70D and ST2000+ for details).

I have just about finalised the layout now but I have a question about STNG network layout that is probably best answered outside the previous thread as it is more general in nature.

My MFD (A70D) is located about 7m (as the cable runs) from the main hub of my network where the STNG/ST1 converter is located.
This distance will have to be covered either by an STNG backbone cable or an STNG spur cable.

I have two options for making this connection:
1. I can connect the MFD via a short spur line to an STNG "T" connector. then run a backbone cable over the longer distance to the Converter.
OR
2. I can run a spur all the way from the MFD to the converter,

As the MFD does not rely on the ST network for its power supply (or vice versa), I'm thinking there is no particular advantage either way but I have seen some posts about keeping spur lines short, so I thought I should check with the gurus.

Could you please advise what is the better option and why?

regards
Dave.

[Derek - Raymarine - Moderator]

HI Dave,
Thankyou for your enquiry.

The general installation of STng is best researched here

In general the rules for STng are the same as for NMEA 2000, spurs should be shorter than 6m and only one device should be connected to a spur. the backbone should be no more than 100m long.

Therefore in answer to your question, you should use Option 1 and extend the backbone closer to the A70D

Regards
Derek

[[email protected]]

Thanks Derek, that is very clear.

[Derek - Raymarine - Moderator]

Hi Dave,

Glad to have helped,
Best regards
Derek