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To get a higher level of abstraction, the CAN signals and messages can be used to abstract the information mappings to the bus communication objects.
Example: The information ‘Nodestatus’ Nodestatus and ‘CPUCPU-Load’ Load shall be sent in a CAN frame called ‘Status’ Status with the following definition:
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4. Payload Byte 1 = CPU-Load
The ‘Nodestatus’ Nodestatus shall be settable via the CAN frame called ‘Command’ Command with the following definition:
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7. Payload Byte 0 = New Nodestatus
If the information ‘Nodestatus’ Nodestatus is changed, the following actions shall be done:
8. New Nodestatus = 1: Start the task ‘LoadLoad-Task’Task
9. New Nodestatus = 2: Stop the task ‘LoadLoad-Task’Task
Source code (Part 1):
#include “cancan_sig.h”h
/* Signal Definition */
enum {
...
0, /* Initial Value */
0 } /* No Callback */
};
Additional Information
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1. The CAN signals can be defined without any CAN communication knowledge. No information about sending or receiving the information is needed during this state.
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Source code (Part 2):
#include “cancan_msg.h”h
/* Message Definition */
enum {
...
0 } } } /* Byte Position */
};
Additional Information
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1. The CAN messages can be defined without any knowledge of the information generation and/or usage of the payload. Only the mapping of information parts to the payload must be known.
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