ST60 Graphic as SeaTalk to NMEA convertor?

[nigelmercier]

I bought a Raymarine ST60 Graphic to add to my chart table pod. It appears to have a SeaTalk to NMEA convertor built-in, any reason why I can't remove my stand-alone E85001 unit?

I seem to recall there was a case for converting the other way (which my E85001 is not wired to do) but I can't remember what the reason was.

 

[Gypsy]

It will depend upon whether the ST60Graphic translates the same Seatalk command set as the E58001 and as a corollary to that what you actually want on the NMEA side. Did the ST60G come with a list of commands/messages it supports?
I know that my 6001 autopilot and RC530 chart each provided a level of ST-NMEA conversion but didn't handle all the commands I needed. In particular there was something I needed to get all my data displayed on my Nav6 screen which I didn't get translated so I ended up buying the E58001. In the end I am pleased I did as it is very versatile as I am sure you have found.

 

[Slipstream 34]

Download the manual it will tell what Nmea sentences it translates. Crucially it does not convert lat and long.

 

[nigelmercier]

... Did the ST60G come with a list of commands/messages it supports?...

Yes, and it does all the ones I want (Wind Speed, Wind Direction, Depth). I'm just thinking there must be a catch.

 

[Plevier]

The only catch I found was that it has a very odd output. If you recall you helped me devise an opto isolator to connect it to my Gamin 750. Worked well. Passed depth, wind, log etc to it.

(In fact come to think of it I didn't use the ST60 graphic for this in the end, i used the ST60 multi, but it's probably the same output stage.)


(Yes my circuit breaks the isolation but isolation wasn't the object. It was much easier to wire that way, it's just stuck on the back of the ST60, avoids an extra wire to the Garmin.)

 

[earlybird]

My Graphic happily converted ST to NMEA, including HDG sentences from the ST60 compass for my Furuno radar. This was to enable radar plotting in conjunction with my Yeoman. However, when I fitted an ST4000 Tillerpilot, the HDG conversion ceased, although the data was still on the ST bus.
Raymarine confirmed, but couldn't explain this, so supplied me with an E85001 unit, which restored the HDG data. This unit seems to have more robust software IMHO. I'd suggest that the OP keeps his.

 

[nigelmercier]

The only catch I found was that it has a very odd output. If you recall you helped me devise an opto isolator to connect it to my Gamin 750. Worked well...

I've been playing with the ST60 Graphic now, and I see what you mean. From your original thread:

... the NMEA+ out is regulated at 11.2V with an 80mA current limit. I don't quite see what the NMEA- does to it...

The NMEA- out is an open-drain pull-down. In other words it acts as a digital on-off switch and pulls the (80mA limited) NMEA+ output down to 0V. The bottom line is that if you connect a dummy load, say 1kΩ, between the terminals then the NMEA output can be taken from the NMEA- and ground. Until you reminded me about your previous thread, I'd been looking at the terminals with an oscilloscope, and saw bugger all! So thank you.

 

[Plevier]

Subsequent to that post I did work it out!
Maybe with some differential input devices your solution would work but I think I tried it with the Garmin and it didn't work because (a) the single sided input expects +ve for on and (b) when you connect as you describe you are draining it through the input impedance which seems to be low.
I haven't gone back over all my notes but that is my recollection.
The opto isolator solution worked first time so I left it at that. Cost under £1 rather than a Rsymarine interface box.

In fact looking at it again, my input to the opto isolator is derived exactly as you suggest isn't it? What I did in effect was to add to the Garmin the differential input stage that they should have fitted to start with!