No longer receiving AIS information - but why?

[MAS3]

OK, took me 2 months to get to it.
But i just took the time to open up the cable and find the orange, blue, yellow and brown wire.
Connected it to my setup usig an optical isolation adapter so the levels are correct.
Now i have the data coming in over the USB connector, and over com 2.
Next thing to test, is to see if things will still be OK if i connect the receiver without the adapter.
But i'll have to change the cable i used for that so that's for tomorrow.
Next to that will be a test to see if i can feed GPS data into the orange / blue wires, and whether these data will be multiplexed with AIS data at the output.
Remind that GPS input is @4800 baud, and output is @38400 baud.
That too will take some time to setup a GPS receiver and some cables.
So i'll be back with the results of that.

By the way: earlier i spoke of RS485 , but that was incorrect.
It is RS 422, which is supposed to be the type of comms in NMEA.
The data is compatible with RS 232, but the levels are different.
If only 1 RS 232 device is connected and no other devices, it will still work in most cases.
RS 485 is a 2 wire bus system, meaning any device can send as wel as receive data over the same 2 wires.

[Mike Two Moons]

Hi:
I have concluded that the unit is defective. Working with the manufacturer who provided additional software which displayed the data stream for the AIS, indicated nothing was being generated.

Repair is not feasable. It costs more than replacement.

Thanks for your input.....Mike

[MAS3]

Hi Mike.

It's a shame that this didn't work out for you.
Nevertheless, i put these things out on these forums so other people might also benefit from it.
I would love to check out the unit to see if it can be revived again.
But you being in Ontario and me in the Netherlands, it wouldn't going to be worth sending it over.

So still i checked the two remaining things out just now.
Connecting the RS 422 output (brown and yellow) directly to a pc's comport, works just fine.
You do not need an adapter for that, as long as it is for recreational use.
(Meaning one should use such adapter in a professional / industrial setup like commercial vessels).

Then the external NMEA.
I connected a JRC 124 GPS antenna (have it over here because it is supposed to have some quirk i'd like to fix) to this input, but nothing happened.
Then i connected it using a NMEA multiplexer.
There is nothing to multiplex, so only this unit is at the output, but this output is also isolated.
I now have position and AIS data available on my test setup here at home.

The receiver indeed does read the position data (and any other data transmitted) from the GPS @ 4800 baud, and retransmits them by including them in the received AIS data @ 38400 baud.
It is available at the RS 422 as well as at the USB connection.

[rgleason]

I just mention that sometimes using a multimeter to see where there is current/voltage change, provides clues. I don't have an AIS, but this really helped with a GPS PS2 Puck where the wiring was not in conformance with the diagram.