2021-04-12, 01:20 PM
(2021-04-12, 01:02 PM)Techstyle Wrote:(2021-04-12, 10:56 AM)dreisday Wrote:(2021-04-11, 02:08 AM)Techstyle Wrote: yes, nice work!!
can you give more details on the AIS transponder and the GPS connection? also, how it is wired to the serial port and which RS422-USB device did you use? these connections can be more difficult than they should be
Hi, thanks for the feedback.
The AIS I used is this: https://www.aliexpress.com/wholesale?cat...ext=ha-102 (there's a few options and I can't find the listing I used)
These are the RS422 adapters I'm using: https://www.ebay.co.uk/itm/New-USB-2-0-t...3059106617
And I used these rewireable serial plugs to tidy up the connections: https://www.ebay.co.uk/itm/DB9-Female-D-...3823152028
I would need to check which way round the connections are when I go to the boat next weekend, but effectively the Orange and Brown from the AIS go into the A/B terminals of one adapter (Pins 1 and 2) which is configured in Signal K as a 38400-baud device. The GPS repeater and radio NMEA input lines are connected to the A/B terminals of the second serial adapter which is configured in Signal K at 4800-baud and set to output nmea0183out events. These events are generated by the signalk-to-NMEA0183 plugin on the Signal K server.
Do you have a GPS antenna connected to the AIS unit or is the AIS unit receiving GPS from elsewhere (Pi?)?
the serial port wiring was as you would have expected it to be? the reason I ask is that on one example I had to flip the positive and negatives (TX+ went to RX- and vice versa)
Cheers
The AIS has its own GPS antenna and is the primary GPS source for the whole system, the serial connection provides both GPS and AIS sentences to the Pi.
I recall having to reverse the wires on the serial connection for the AIS. I believe this is because although NMEA0183 is supposed to use separate +/- conductors for Tx and Rx, many manufacturers don't properly implement this aspect of the standard, making the actual wiring more like RS232 with a common ground rather than RS422.
I didn't have an issue on the output side - I believe as my implementation is fully compliant to the standard by using a proper RS422 adapter so it just worked with the other devices on the boat.