[CA] [CA11] A78 Integrated with ST1 Network

[PJE56]

I'm help a friend out. He has a A78 MFD (E70202), an i40 bi-data and ST4000+ wheel pilot. I figured that a ST 1 cable can connect the i40 to the ST4000+ and then a ST1 - to NG converter can be connected to the ST4000. The A78 then connects into the converter with an NG spur cable.

The issue I am concerned about is power. The ST4000+ docs states that the direct connected 12VDC should be used and not power from the ST1 network; I understand that and it's fine. I will have the i40 direct power disconnected. I read in a thread here about a similar integration, that the power from the ST1 network should not be passed to the converter and the NG network. The suggestion was to cut the red wire on the ST1 converter cable. Is this the recommend solution or was this just because of the number of devices on the ST1 network? (This will only have 2 on the ST1).

My other question is if the A78 has the power cable connected will it power the ST ng bus? Or will additional 12vdc tap be required for the ng bus?

Thanks in advance.

Paul

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Paul,

Q1. Is this the recommend solution or was this just because of the number of devices on the ST1 network? (This will only have 2 on the ST1).
A1. It is recommended that the SeaTalk to SeaTalkng Converter be powered via the supplied SeaTalkng Power Cable which in turn will be interfaced to a switched 12VDC power circuit which will be protected with a 5A fuse. The SeaTalk to SeaTalkng Cable supplied with the SeaTalk to SeaTalkng Converter Kit will be interfaced to a D224 SeaTalk Junction Block. A pair of SeaTalk Cables having press-fit 3-pin plugs will be connected to the D244 SeaTalk Junction Block. One of these SeaTalk Cables will be connected to the i40 instrument and the second SeaTalk Cable will be connected to the ST4000+. The latter SeaTalk Cable should be cut at a convenient location and then spliced back together, leaving its red lead unspliced. The SeaTalk Cable's red leads will then be insulated to prevent shorting. Doing so will prevent the ST4000+ from supplying power to the SeaTalk buss. In this way, the i40 instrument will be powered by the backbone via the the SeaTalk to SeaTalkng Converter.

While it is technically possible to do as you have suggested, it not considered to be a best installation practice, it may be the most expedient solution for simply adding an a78 MFD alone to a system. It is considered to be a best installation practice to power the SeaTalk bus from the SeaTalkng backbone via a SeaTalk to SeaTalkng Converter to prepare the way for any future expansion or replacement of equipment. As Raymarine is moving away from SeaTalk in favor of SeaTalkng / NMEA 2000 to for greater communications performance, simplified installation and to permit greater compatibility with third party products, it is far more likely that any future products added to ones system will feature a SeaTalk communications interface rather than a SeaTalk interface. As such, powering from the backbone will potentially eliminate the possibility of drawing too much power from a SeaTalk bus through the SeaTalk to SeaTalkng Converter.


Q2. My other question is if the A78 has the power cable connected will it power the ST ng bus?
A2. Negative. Raymarine MFDs are not designed to supply power to a SeaTalkng / NMEA 2000 bakcbone.

Q3. Or will additional 12vdc tap be required for the ng bus?
A3. See the response to Q1.