[TG] [TG11] SeaTalk 1 to MNEA 2000 via ST70

[HaraldS]

I have a few questions interfacing SeaTalk 1 to NMEA2000. Found some of the answers in your Forum but not all.

I have an existing SeaTalk 1 based system ,consisting of an S3G course computer, 1 ST7002+, 1 ST6000+, 1 ST600R, 1 smart controller w. Base station, 1 ST60 Multi, ST60 Speed, ST60 Depth, ST 60 Wind, ST 60 close hauled, and 1 ST70 instrument. Also there are still 2 SeaTalk 1 to NMEA0183/RS232 bridges that I may not use any more.

The SeaTalk 1 bus with all above listed instruments is powered by the S3G.

The functions (PGNs) I would like to get from SeaTalk 1 to NMEA2000 are wind, water speed and depth related data, as well as rudder angle and heading. The other way I would like to send GNSS data like position, SOG, SOG, and autopilot (RMB type) data to facilitate track mode. Fast heading I have already picked up directly at the NMEA0183 port of the S3G and passed it via an Actisense gateway to the N2k backbone - that works just fine and is used as backup heading should the Airmar 220WX sensor fail.

To bridge between the SeaTalk1 network and the NMEA2000 backbone and get the above function, it looked to me like I had about three options.

1) ST70 instrument bridging to the NMEA2000 backbone using spur cable A06046.

2) Using a SeaTalk1 to SeaTalkng converter kit E22158 and splicing a backbone cable to connect it with the NMEA2000 backbone.

3) Using one of the SeaTalk 1 to NMEA0183/RS232 bridges in conjunction with another Actisense N2k/N0183 gateway.

Since I already had the ST70 instrument I tried version (1) and it appeared to work right away. However I noticed that the ST70 would occasionally freeze and not get going again without cycling power. I also noticed that it was passing on SeaTalk power to the N2k backbone. I actually found this quite convenient as I would need to power N2k from an inverter as my DC system is 24V. Checked the S3G and it claims to provide up to 5A for SeaTalk power. The load on the N2k backbone is rather mild as the bigger participants have their own power supply. What’s left is currently two Actisense gateways with 35mA (LEN1), 1 Yacht Devices gateway with 18mA (LEN1) and one Airmar 220WX sensor with <50mA (LEN1).

I have not tried version (2) as I don’t have the conversion kit (yet) and I’m not sure if it would be any different to using the ST70 for the same task. I realise that the ST70 is a bit dated and the reason for it to occasionally freeze may simply lay in the fact that N2k specs have advanced since and some new PNG format may confuse it. It has worked flawlessly as long as it was just connected to good old SeaTalk 1. So one of my questions is, would the conversion kit be a save bet, and the best way to do this?

With respect to version (3), I have not tried it yet, but am quite sure it would work ok. It just seems a bit odd to translate twice. With version (3) the choice of SeaTalk power for N2k goes away and I would need to separately power the two networks.

So, am I making some false assumptions and/or is there a best way of solving this that you would recommend.

Regards Harald