after uploading the firmware I did not used the Get Accelerometer data option, I skpied to the hardware config and did check off the MAVLINK enable and depoly my model after that it is worked. when i did upload the firmware again the Get Accelerometer data option starts working.
Once you have successfully uploaded the firmware, you cannot use the Get Accelerometer data option in Test Connection screen. This is because it treats the bootloader COM port as the main communications port. This is a limitation in R2021b. If you have uploaded the firmware successfully, exit the Hardware Setup screen and configure the Simulink® model accordingly to set the upload and communication port. For more information, see Set COM Port for Upload and Communication in Simulink.