May I place DSC call through chartplotter AIS target?

[stevead]

Can a DSC radio set-up a DSC call based on input to the radio via NMEA-0183 using a standard sentence?

Yes, Icom radios such as the M504 can initiate a DSC call upon the reception of the appropriate NMEA 183 DSC sentence. It's a long time since I played with this but if I remember correctly something like

$CDDSC,20,503112090,00,00,26,900072900072,,,,,R*16

should initiate a VHF DSC call to 503112090 on VHF channel 72.
I'll leave it as an exercise for the reader to peruse Recommendation ITU-R M.493-15 to work out how to send all ships calls, position requests, etc.
I should add however, that I have never dared to try to initiate a DSC Distress call, for obvious reasons.

[CaptainFlint]

When you are crossing shipping lanes at night it would be very handy to be able to make a DSC call directly from the chart-plotter AIS. it makes it easier than hailing a ship on Ch16 especially if you are alone on watch or short-handed. I have hailed ships on CH16 and not had a response but DSC generally works with ships as they are professional mariners!