External Mode Open Protocol Connect command failed
Caused by:
The model that you are trying to run in External mode does not match the application running on your target. Checksum test (OPEN_PROTOCOL) failed. The host model’s structural checksum is [2526462847, 2787246958, 279442647, 1167683516] and the target application’s structural checksum is [3758715623, 2604559863, 3074017724, 3602092489]. Rebuild the model, run it on your target, and start External mode simulation again.
Component:Simulink | Category:Block diagram error
Unable to connect to the ‘Raspberry Pi’ target for

Solution: Delete the related files of the model in the Raspberry Pi
(1) View the file directory

ls /home/pi/

(2) Open the matlab file directory in the raspberry pie

cd MATLAB_ws/R2020b

(3) Delete the elf and log related to the model
for example:

rm -f CANComm_Gear_control.log