Published in J15765

Mapping of the N_PDU fields - from ISO15765-2

Addressing formats 

The exchange of network layer data is supported by three addressing formats: normal, extended and mixed addressing. Each addressing format requires a different number of CAN frame data bytes to encapsulate the addressing information associated with the data to be exchanged. Consequently, the number of data bytes transported within a single CAN frame depends on the type of addressing format chosen.

The following (7.3.2 to 7.3.5) specifies the mapping mechanisms for each addressing format, based on the data link layer services and service parameters defined in ISO 11898-1.

7.3.2        Normal addressing 

For each combination of N_SA, N_TA, N_TAtype and Mtype, a unique CAN identifier is assigned. N_PCI and N_Data is placed in the CAN frame data field. See Table 19.

Table 19 — Mapping of N_PDU parameters into CAN frame — Normal addressing 

 

N_PDU type

 

CAN Identifier

CAN frame data field

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

Byte 7

Byte 8

SingleFrame (SF)

N_AI

N_PCI

N_Data

FirstFrame (FF)

N_AI

N_PCI

N_Data

ConsecutiveFrame (CF)

N_AI

N_PCI

N_Data

FlowControl (FC)

N_AI

N_PCI

N/A

 

 7.3.3 Normal fixed addressing 

Normal fixed addressing is a subformat of normal addressing where the mapping of the address information into the CAN identifier is further defined. In the general case of normal addressing, described above, the correspondence between N_AI and the CAN identifier is left open.

For normal fixed addressing, only 29 bit CAN identifiers are allowed. Tables 20 and 21 define the mapping of the address information (N_AI) into the CAN identifier, depending on the target address type (N_TAtype). N_PCI and N_Data is placed in the CAN frame data field.

Table 20 — Normal fixed addressing, N_TAtype = physical 

 

N_PDU type

29 bit CAN Identifier bit position

CAN frame data field byte position

28 ... 26

25

24

23 ... 16

15

8

7 ... 0

1

2

3

4

5

6

7

8

SingleFrame (SF)

110 (bin)

0

0

218 (dec)

N_TA

N_SA

N_PCI

N_Data

FirstFrame (FF)

110 (bin)

0

0

218 (dec)

N_TA

N_SA

N_PCI

N_Data

ConsecutiveFrame (CF)

110 (bin)

0

0

218 (dec)

N_TA

N_SA

N_PCI

N_Data

FlowControl (FC)

110 (bin)

0

0

218 (dec)

N_TA

N_SA

N_PCI

N/A

 

Table 21 — Normal fixed addressing, N_TAtype = functional 

 

N_PDU type

29 bit CAN Identifier bit position

CAN frame data field byte position

28 ... 26

25

24

23 ... 16

15

8

7 ... 0

1

2

3

4

5

6

7

8

SingleFrame (SF)

110 (bin)

0

0

219 (dec)

N_TA

N_SA

N_PCI

N_Data

FirstFrame (FF)

110 (bin)

0

0

219 (dec)

N_TA

N_SA

N_PCI

N_Data

ConsecutiveFrame (CF)

110 (bin)

0

0

219 (dec)

N_TA

N_SA

N_PCI

N_Data

FlowControl (FC)

110 (bin)

0

0

219 (dec)

N_TA

N_SA

N_PCI

N/A


7.3.4        
Extended addressing 

For each combination of N_SA, N_TAtype and Mtype, a unique CAN identifier is assigned. N_TA is placed in the first data byte of the CAN frame data field. N_PCI and N_Data is placed in the remaining bytes of the CAN frame data field.

Table 22 — Mapping of N_PDU parameters into CAN frame — Extended addressing 

N_PDU type

CAN Identifier

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

Byte 7

Byte 8

SingleFrame (SF)

N_AI, except N_TA

N_TA

N_PCI

N_Data

FirstFrame( FF)

N_AI, except N_TA

N_TA

N_PCI

N_Data

ConsecutiveFrame (CF)

N_AI, except N_TA

N_TA

N_PCI

N_Data

FlowControl (FC)

N_AI, except N_TA

N_TA

N_PCI

N/A

 

 7.3.5       Mixed addressing 

7.3.5.1       29 bit CAN identifier 

Mixed addressing is the addressing format to be used if Mtype is set to remote diagnostics.

Tables 23 and 24 define the mapping of the address information (N_AI) into the 29 bit CAN identifier scheme and the first CAN frame data byte, depending on the target address type (N_TAtype). N_PCI and N_Data are placed in the remaining bytes of the CAN frame data field.

Table 23 — Mixed addressing with 29 bit CAN Identifier, N_TAtype = physical 

 

N_PDU type

29 bit CAN Identifier bit position

CAN frame data field byte position

28 ... 26

25

24

23 ... 16

15

8

7 ... 0

1

2

3

4

5

6

7

8

SingleFrame (SF)

110 (bin)

0

0

206 (dec)

N_TA

N_SA

N_AE

N_PCI

N_Data

FirstFrame (FF)

110 (bin)

0

0

206 (dec)

N_TA

N_SA

N_AE

N_PCI

N_Data

ConsecutiveFrame (CF)

110 (bin)

0

0

206 (dec)

N_TA

N_SA

N_AE

N_PCI

N_Data

FlowControl (FC)

110 (bin)

0

0

206 (dec)

N_TA

N_SA

N_AE

N_PCI

N/A

 
Table 24 — Mixed addressing with 29 bit CAN Identifier, N_TAtype = functional 

 

N_PDU type

29 bit CAN Identifier bit position

CAN frame data field byte position

28 ... 26

25

24

23 ... 16

15

8

7 ... 0

1

2

3

4

5

6

7

8

SingleFrame (SF)

110 (bin)

0

0

205 (dec)

N_TA

N_SA

N_AE

N_PCI

N_Data

FirstFrame (FF)

110 (bin)

0

0

205 (dec)

N_TA

N_SA

N_AE

N_PCI

N_Data

ConsecutiveFrame (CF)

110 (bin)

0

0

205 (dec)

N_TA

N_SA

N_AE

N_PCI

N_Data

FlowControl (FC)

110 (bin)

0

0

205 (dec)

N_TA

N_SA

N_AE

N_PCI

N/A

 
7.3.5.2            11 bit CAN identifier 

Mixed addressing is the addressing format to be used if Mtype is set to remote diagnostics.

Table 25 defines the mapping of the address information (N_AI) into the 11 bit CAN identifier scheme. For each combination of N_SA, N_TA and N_TAtype a unique CAN identifier is assigned. N_AE is placed in the first data byte of the CAN frame data field. N_PCI and N_Data is placed in the remaining bytes of the CAN frame data field.

Table 25 — Mixed addressing (11 bit CAN Id) 

 

N_PDU type

 

CAN Identifier

 

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

Byte 7

Byte 8

SingleFrame (SF)

N_AI

N_AE

N_PCI

N_Data

FirstFrame( FF)

N_AI

N_AE

N_PCI

N_Data

ConsecutiveFrame (CF)

N_AI

N_AE

N_PCI

N_Data

FlowControl (FC)

N_AI

N_AE

N_PCI

N/A



Annex A

(informative)

Use of normal fixed and mixed addressing with data link layer according to SAE J1939 

A.1    Overview 

This annex describes how to map address information parameters, N_AI, into the CAN frame when a data link layer according to SAE J1939 is used.

A.2    Rules 

A.2.1    Normal fixed addressing 

Table A.1 shows the mapping of address information parameters, N_AI, into the CAN frame when Network Target Address type, N_TAtype, physical addressing is used.

Table A.1 — Normal addressing, physical addressed messages 

J1939 name

P

R

DP

PF

PS

SA

Data field

Bits

3

1

1

8

8

8

64

Content

default 110 (bin)

0

0

218 (dec)

N_TA

N_SA

N_PCI, N_Data

CAN Id Bits

28 – 26

25

24

23 – 16

15 – 8

7 – 0

 

CAN data byte

           

1 – 8

CAN Field

Identifier

Data

 
Table A.2 shows the mapping of address information parameters, N_AI, into the CAN frame when Network Target Address type, N_TAtype, functional addressing is used.

Table A.2 — Normal addressing, functional addressed messages 

J1939 name

P

R

DP

PF

PS

SA

Data field

Bits

3

1

1

8

8

8

64

Content

default 110 (bin)

0

0

219 (dec)

N_TA

N_SA

N_PCI, N_Data

CAN Id Bits

28 – 26

25

24

23 – 16

15 – 8

7 – 0

 

CAN data byte

           

1 – 8

CAN Field

Identifier

Data


 
A.2.2 Mixed addressing 

Table A.3 shows the mapping of address information parameters, N_AI, into the CAN frame  when the Network Target Address type, N_TAtype, physical addressing is used.

Table A.3 — Mixed addressing, physical addressed messages 

J1939 name

P

R

DP

PF

PS

SA

Data field

Bits

3

1

1

8

8

8

8

56

Content

default 110 (bin)

0

0

206 (dec)

N_TA

N_SA

N_AE

N_PCI, N_Data

CAN Id Bits

28 – 26

25

24

23 – 16

15 – 8

7 – 0

   

CAN data byte

           

1

2 – 8

CAN Field

Identifier

Data

 
Table A.4 shows the mapping of address information parameters, N_AI, into the CAN frame when Network Target Address type, N_TAtype, functional addressing is used.

Table A.4 — Mixed addressing, functional addressed messages 

J1939 name

P

R

DP

PF

PS

SA

Data field

Bits

3

1

1

8

8

8

8

56

Content

default 110 (bin)

0

0

205 (dec)

N_TA

N_SA

N_AE

N_PCI, N_Data

CAN Id Bits

28 – 26

25

24

23 – 16

15 – 8

7 – 0

   

CAN data byte

           

1

2 – 8

CAN Field

Identifier

Data

 
A.2.3 Priority (P) 

The priority is user defined with a default value of six (6).

The three bits priority field is used to optimize message latency for transmission onto the CAN bus only. The priority field should be masked off by the receiver (ignored). The priority of any CAN message can be set from highest, 0 (000 bin), to lowest, 7 (111 bin).

A.2.4   Reserved bit (R) 

The reserved bit shall be set to “0”.

A.2.5   Data Page (DP) 

The data page bit shall be set to “0”.

A.2.6   Protocol data unit format (PF) 

The format is of the type PDU1, “destination specific”. 

Diagnostic messages shall use the following parameter group numbers (PGN).

  • Mixed addressing: 52480 (dec) for N_TAtype = functional, which gives PF = 205 (dec).
  • Mixed addressing: 52736 (dec) for N_Tatype = physical, which gives PF = 206 (dec).
  • Normal fixed addressing: 55808 (dec) for N_TAtype = physical, which gives PF = 218 (dec),
  • Normal fixed addressing: 56064 (dec) for N_TAtype = functional, which gives PF = 219 (dec).

A.2.7    PDU-specific (PS) 

The PDU-specific field shall contain the target address (destination address), N_TA.

A.2.8    Source Address (SA) 

The SA field shall contain the source address, N_SA

A.2.9    Update rate 

Update rate is according to user requirements.

A.2.10   Data length 

Data length shall be eight (8) bytes. 

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