B&B Electronics HVD100A3 manual Transmit Data to J1939 Bus, Set Mask, MSB-1 MSB-2

Transmit Data to J1939 Bus

Byte	Byte	Function
Number	Value
1	01	Start of frame
2	06	Control bytes
3	02	ID byte 1 = J1708 message
4	02	Function byte 02 transmit message
5	XX	MSB of arbitration field (J1939 priority bits)
6	XX	MSB-1
7	XX	MSB-2
8	XX	LSB of arbitration field (J1939 source address)
9	DD	Number of data bytes
	DATA	From 0 to 8 bytes
	CS	Checksum

Set Mask

Function code 04 set mask. The mask is applied to ALL filters. The mask is 32 bits long. The last 3 bits are not used and must be set to zero. This mask covers the 29-bit arbitration field. To use the filter function, the mask must be set. The mask determines what position(s) will be tested and matched to the incoming message. If a 1 is set in a particular position, that position will be tested. It will be “and” with any active filters to determine if the message will be passed to the PC side. Any position marked with a 0 is a “don’t care” position and will pass all data in that position. There is a form on page 33 that helps set up the mask for the arbitration field.

Byte	Byte	Function
Number	Value
1	01	Start of frame
2	06	Control bytes
3	02	ID byte 02 = J1939
4	04	Function byte 04 set mask
5	XX	MSB of arbitration field (J1939 priority bits)
6	XX	MSB-1
7	XX	MSB-2
8	XX	LSB of arbitration field (J1939 source address)
9	00	Number of data bytes
10	CS	Checksum
HDV100A3 Command & Response Manual-1306cr			23

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