Hi,
To transmit more than 8 bytes of data using a single CAN frame ID, you can implement a multipacket transmission strategy. This involves splitting your data into multiple CAN frames and then reassembling them on the receiving end. Here's a basic approach using Simulink blocks:
Steps for Multipacket Transmission
1. Data Preparation:
- Split your data into chunks of 8 bytes or less. For 13 bytes of data, you will need at least two CAN frames.
2. Indexing and Sequencing:
- Use an index or sequence number to keep track of the order of the packets. This helps in reassembling the data correctly at the receiver.
3. Simulink Model Setup:
- Signal Builder/Constant Block: Use this block to create your data signal.
- Demux Block: Split your data into 8-byte chunks.
- CAN Transmit Blocks: Use multiple CAN Transmit blocks, each configured to send a chunk of data. Assign the same CAN ID to each block but differentiate them using sequence numbers or flags in the data payload.
4. Include Control Information:
- Use a part of the CAN data payload to include control information such as sequence numbers or a start/end flag to indicate the beginning or end of a data sequence.
5. Timing Control:
- Use a Clock or Counter block to control the timing of each transmission, ensuring that frames are sent in the correct order and at appropriate intervals.
6. Reassembly at Receiver:
- On the receiving end, use a similar sequencing mechanism to reassemble the data. You can use a CAN Receive block to capture incoming frames and a MATLAB Function block to handle reassembly logic.
Example Implementation
Here is a basic outline of how you might set this up in Simulink:
[Data Source] --> [Demux] --> [CAN Transmit 1]
--> [CAN Transmit 2]
- Data Source: This could be a constant block or a signal builder that simulates your data stream.
- Demux Block: Splits the data into two signals, each 8 bytes or less.
- CAN Transmit Blocks: Each block is configured to send one of the data chunks. Ensure that each block sends data with a sequence number or identifier in the data payload.
Additional Considerations
- Error Checking: Implement error checking and handling mechanisms to ensure data integrity.
By following these steps, you can effectively implement a multipacket transmission strategy using basic Simulink blocks. This method allows you to transmit larger data sets over a CAN network while maintaining data integrity and order.
