The external mode data is uploaded to the host for display through Simulink's external mode buffers. This error occurs because, the size of the external mode buffer might be too large. In order to resolve this issue, so that the data will be displayed, the buffer size should be reduced. To reduce the size of the buffer, either increase the model's base rate so that it is faster or reduce the number of base rate samples used in the model's external mode buffer by decreasing the Duration in the Signal & Triggering menu under Tools > External Mode Control Panel > Signal & Triggering.
Please follow the steps shown below to resolve this issue.
1. Please open your model
2. Go to code -> External Mode Control Panel
3. Click on 'Signal & Triggering...'
4. Try to reduce the number in 'Duration' text box to 5.