A:
Due to CAN network design, CAN frames may not be transmitted as specified.
There are various possible reasons why data is not transmitted as specified,
but we recommend that you first check the following three points.
Note that it is common to obtain a dedicated CAN analyzer separately and check the communication status of the CAN network.
Please reduce the amount of data transmitted so that the amount of CAN communication used is approximately 30% to 40%.
The larger the ratio of communication usage to the maximum
communication capacity of the communication line (the higher the communication
load), the longer the CAN communication transmission process will be delayed.
In some cases, it appears that the specified data is not being
transmitted.
Please understand the status and how often each CAN ID is being transmitted.
In CAN communication, the CAN frame with the smaller CAN
ID is given priority.
If there are many CAN frame transmissions or the CAN frame
transmission period is short, the CAN bus will be occupied by CAN frames
with the small CAN ID.
As a result, transmission of CAN frames with large CAN ID will
be significantly delayed.
If a CAN frame with the small CAN ID is occupying the CAN bus, lengthen the transmission period or reduce the amount of data being transmitted.
Please understand the state of which CAN device transmits the CAN frame of which CAN ID in which period.
When multiple CAN devices transmit CAN frames with the same
CAN ID at the same time, Arbitration
Field mechanism may break down,
and the state in which Data
Field of the transmitted CAN frame differs from Data
Field on the actual CAN bus may occur consecutively.
In this case, the bus will be off and no data will be transmitted
at all.
For information about Arbitration Field and Data Field, please refer to the topic [Difference between CAN 2.0B Communication and CAN FD Communication].