Error while executing external mode on Arduino Mega

I was trying to build a Simulink model into Arduino Mega 2560 but got an error as follows:-

"Error occurred while executing External Mode MEX-file 'ext_comm': ExtGetTargetPkt() call failed while checking target pkt header. Component:Simulink | Category:Block diagram error Error occurred while executing External Mode MEX-file 'ext_comm': ExtSetTargetPkt() call failed on CLOSE. Ensure target is still running"

Please tell me what is wrong with my model... I have attached my model and error message on diagnostic viewer with this question.

[Madhu Govindarajan]

I feel like the sample time might be the issue. Have you tried changing that?

[Omkar Bhanap]

according to the block parameters, minimum sample time that we can set is 1 micro second. I have fixed it to 100 micro seconds. So I dont think that there is any problem with sample time.

[Madhu Govindarajan]

You are correct in that the sample time can be set to 1 micro second. But when you are streaming data over serial (External mode) it might not necessarily work.

You can try and slow the sampling time down to something absurdly slow (like 1/10th a of second) and check if this is causing the issue. If it is, then you can adjust different parameters appropriately. If it is not, at least you know for sure that this is not the reason.

[Omkar Bhanap]

I changed sample time to 0.001second but, still got the same problem. Can you please tell me what might be the reason behind that, Sir ?

[Madhu Govindarajan]

I ran the model in your attached file without any error messages when I disabled the overrun detection option. I got the same error message when I enabled overrun detection option at 1K Hz sampling time - Error:Error occurred while executing External Mode MEX-file 'ext_comm': ExtGetTargetPkt() call failed while checking target pkt header.

Hopefully that helps. If not, I would recommend slowing the sampling time both on the block and at the model level to 100 Hz or 1 Hz. If that also does not work, please reach out to MathWorks Technical support and they should be able to assist you with this.

[Omkar Bhanap]

Not working on my model. How can I get help from Mathworks Technical Support Assist Team ??