Installation Manual

AIS Installation Manual Issue 1 37
7.4.19 LRI - AIS long-range interrogation
Long-range interrogation is a mechanism that allows one AIS unit to request certain data from
another AIS unit through the use of a number of interrogation and reply sentences.
When the transponder receives an LRI and LRF sentence pair on its Long Range port, it
forwards them on to all the presentation ports. If the transponder has been configured to provide
and automatic response to the interrogation then it does so; otherwise it waits for the sentences
to be returned to it (on any presentation port) before responding.
$--LRI,x,a,xxxxxxxxx,xxxxxxxxx,llll.ll,a,yyyyy.yy,a,llll.ll,a,yyyyy.yy,a*hh<CR><LF>
longitude, E/W (SW coordinate)
latitude, N/S (SW coordinate)
longitude, E/W (NE co-ordinate)
latitude, N/S (NE co-ordinate)
MMSI of destination
MMSI of requestor
control flag
sequence number
7.4.20 RMC – recommended minimum specific GNSS data
This sentence is used to transmit the time, data, position, course and speed data from a GNSS
navigation receiver. The sentence is transmitted at least once every two seconds from GNSS
device(s) and is always accompanied by an RMB sentence when a destination waypoint is
active.
$--RMC,hhmmss.ss,A,llll.ll,a,yyyyy.yy,a,x.x,x.x,xxxxxx,x.x,a,a*hh<CR><LF>
mode indicator (‘A’, ‘D’, ‘E’, ‘M’ ->
used; ‘N’ -> invalid)
magnetic variation
date
course over ground
speed over ground
londitude, E/W
latitude, N/S
status (‘A’ -> use mode field; ‘V’ ->
use fields as default values)
UTC of position fix
Note that RMC has priority over VTG.
7.4.21 ROT – rate of turn
This sentence provides the rate and direction of turn.
$--ROT,x.x,A*hh<CR><LF>
status (‘A’ -> rate of turn is valid)
rate of turn
7.4.22 TXT – text transmission
This sentence is used for transmitting text messages such as alarm messages from a sensor or
the transponder to any presentation display device such as the M-2 display unit.
$--TXT,xx,xx,xx,c--c*hh<CR><LF>
text message
text identifier
message number
total number of messages