motorola协议解析

1、协议中Type是指Message Type，P是指Periodic message （注：The message is transmitted on a periodic basis only. The signals in the Periodic message do not have the ability to generate an event transmission of the message. All signals in a message may not have the same requirements on up-date time. Signals that have a lower requirement on the up-date time than the periodicity of the periodic message do not have to be up-dated every time the message is sent. However, the up-date time requirement has to be fulfilled for each signal, as defined by the Signal Age.）

2、协议中是motolora格式；

3、电池的总电流偏置-1600，是确定的格式，（当D=32000时，电流为0A。）

附：

Position of signal in the CAN frame

Each signal occupies a number of bit-positions in the Message Map, as indicated by the position range.

The relation between the bit-positions used in the Message Map and the Byte/Bit position in the CAN frame is a static representation as illustrated in Table 1. Byte #0 in the table corresponds to the first data byte transmitted or received in the CAN frame, and Byte #n ( “n” is included between 0 and 7) is the last byte.

Bit #7 is the most significant bit in the byte.

Transmitting a message with 8 byte length on the bus, bit 7 (most significant bit of byte 0) will be transmitted first, followed by bit 6. Bit 56 (least significant bit of byte 7) will be transmitted at last.

Bits row out:

7,6,5,4,3,2,1,0,15,14,13,12,11,10,9,8,23, ………………,40,55,54,53,52,51,50,49,48,63,62,61,60 ,59,58,57,56

When a Module receives a message, the first bit received will be the bit located at position 7 in

Table 1: Illustration of Message Map bit positions in a CAN frame

Accessing the Signal within a 64 bits block requires a common indexing standard; “Motorola Forward LSB” notation has been adopted.

Example:

Let us assume a Signal called “RPM” has:

- Its least significant bit on bit 16 of the 64 bits data field;

- 12 bits data length