When using NI-XNET for CAN or CAN FD communication, there is a limit to the total number of connections to the channel from MATLAB® or Simulink®.
To work around this issue in Simulink:
Use only a single Receive block for message reception in Simulink and connect all downstream Unpack blocks to it.
Use a Mux block to combine CAN messages from Unpack blocks transmitting at the same rate into a single Transmit block.
To work around this issue in MATLAB:
Try reusing channels you have already created for your application.