ACR Electronics Y1-03-0222 VHF data link own vessel messages Nmea 0183 VDO, VDO message format

5.VHF data link own vessel messages (NMEA 0183 VDO)

This message describes your own vessel message being sent.

VDO message format

!--VDO,x1,x2,x3,a,s--s,x*hh<CR><LF> field 1 2 3 4 5 6

Field	Format	Description
1	x	Total number of sentences needed to transfer the message1, 1 to 9
2	x	Sentence number1, 1 to 9
3	x	Sequential message identifier2, 0 to 9
4	a	AIS Channel, "A" or "B"3
5	s---s	Encapsulated ITU-R M.1371 radio message4
6	x	Number of fill-bits5, 0 to 5

NOTE 1 The length of an ITU-R M.1371 message may require the transmission of multiple sentences. The first field specifies the total number of sentences used for a message, minimum value 1. The second field identifies the order of this sentence in the message, minimum value 1. These cannot be null fields.

NOTE 2 The Sequential message identifier provides a message identification number from 0 to 9 that is sequentially assigned and is incremented for each new multi-sentence message. The count resets to 0 after 9 is used. For a message requiring multiple sentences, each sentence of the message contains the same sequential message identification number. It is used to identify the sentences containing portions of the same message. This allows for the possibility that other sentences might be interleaved with the message sentences that, taken collectively, contain a single message. This shall be a null field for messages that fit into one sentence.

NOTE 3 The AIS channel is indicated as either “A” or “B”. This channel indication is relative to the operating conditions of the AIS unit when the packet is received. This shall be a null field when the channel identification is not provided. The VHF channel numbers for channels “A” and “B” are obtained by using a “query” (See IEC 61162-1, clause 5.3.2) of the AIS unit for an ACA sentence.

NOTE 4 This field supports a maximum of 62 valid characters for messages transferred using multiple sentences, and 63 valid characters for messages using a single sentence.

NOTE 5 This cannot be a null field. (See “x4” in IEC 61162-1, clause 5.3.3).

	VDO Message number	VDO Message description
	AIS Target Display Information
13		Safety Related Acknowledgement
18		Standard Class B position report (Includes MMSI, SOG, position accuracy, lat,
		long, COG, true heading,)
	24a	Class B “CS” Static data Part A (Includes MMSI and vessel name)
	24b	Class B “CS” Static data Part B (MMSI, ship type, cargo type, call sign, ship
		dimensions)

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Y1-03-0222 Rev. C