Aids to Navigation monitoring data

Parameter Number of bits Description
Message ID 6 Identifier for this message 6; always 6.
Repeat Indicator 2 Used by the repeater to indicate how many times a message has been repeated.

0 – 3; default = 0; 3 = do not repeat any more.
Source ID 30 MMSI number of source Unit
Sequence Number 2 0 – 3
Destination ID 30 MMSI number of destination Unit.
Retransmit Flag 1 Retransmit Flag should be set upon retransmission:

0 = no retransmission = default

1 = retransmitted.
Spare 1 Not used.  Should be zero.
DAC 10 Destination Area Code.

Default: 235 (UK & NI) or 250 (ROI)
FI 6 Function Identifier

Default: 10 for this GLA standard message
Analogue (internal) 10 0.05- 36V 0.05V step Supply voltage to AIS Unit

0 – Not Used
Analogue (external –

from hardware analogue input No 1

 10 0.05 – 36V 0.05V step

0 – Not Used
Analogue (external –

from hardware analogue input No 2

 10 0.05 – 36V 0.05V step

0 – Not Used
Status Bits   0 / 1

(internal – same as the 5 LSBs of status bits from Message type 21)

 5 4  \ /  00 – no RACON installed;  01 – RACON not monitored

3  / \  10 – RACON operational;  11 – RACON ERROR

2  \ /  00 – no light or no monitoring;  01 – Light ON

1  / \  10 – Light OFF;  11 – Light ERROR

0    0 – Good Health, 1 – Alarm
Status Bits   0 / 1

(external – derived from hardware digital inputs)

 8 7  Digital Input   Off/ / On

:

:

0  Digital Input   Off/ / On
Off Position Status 1 Off position or On position

0:  On position

1:  Off position
Spare 4 For future use.  Should be zero.
TOTAL OF BITS. 136 Occupies 1 slot.