汽车CAN总线参数编号SPN及参数群

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汽车CAN总线参数编号SPN及参数群编号PGN怎么规定的

首先PGN是一个24位的值，包括保留位、数据页位、PF（PDU格式场）和PS（群扩展场）等要素。

在各个位转化到PGN的过程中，如果PF的值小于240（十进制）时，PGN的低字节置零（个人理解当PF的值小于240时，PS的置0）。

举一个例子：请求PGN的数据页位（DP）=0；PF=234（#EA）那么她的参数群编号PGN=#00EA00。因为PF=234<240,所以PS=#00

注：PF（PDU格式场）和PS（群扩展场）都是八位

5.1.2 Parameter Group Number (PGN) (R)

Whenever it is necessary to identify a Parameter Group in the data field of a CAN data frame, it will be

expressed in 24 bits. The 24-bit value is sent least significant byte first (see Table 2 where it is stated the

MSB is sent third, middle byte second and least significant byte first). The Parameter Group Number is a

24-bit value that has the following constituent components: 6 bits set to zero, Reserved bit, Data Page

bit, PDU Format Field (8 bits), and Group Extension Field (8 bits). The procedure for the bit fields to be

converted to a Parameter Group Number is as follows. The six most significant bits of the PGN are set to

zero. Then the Reserved Bit, Data Page bit and PDU Format field are copied into the next 18 bits. Lastly

if the PF value is less than 240 (F016), then the least significant byte of the PGN is set to zero. Otherwise

it is set to the value of the Group Extension Field. Reference Table 2 for an illustration of the constituent

component bit fields and their corresponding PGN decimal number. Note that not all 217 (or 131072)

combinations are available for assignment using the conventions specified in this document. The

conventions specified yield 8672 PGs (calculated as: 2 pages * [240 + (16*256)] = 8672 PGs). The

Cumulative Number of PGs column in Table 2 identifies the number of PGNs possible. See SAE J1939,

Appendix A to see the assigned PGNs

PGN – 参数组号码（Parameter Group Number）

总线上的信息被以“组”的形式广播