STM32F746G Discovery Board UDP Comms not Working

I have a Simulink model running on a STM32F746G Disco board using the STM32 embedded coder support package. I wish to be able to control and monitor the Disco model target using a host Simulink model over UDP. The target model has UDP Send and UDP RCV blocks. The host model has model UDP Receive (HOST) and UDP Send (HOST) blocks. Host PC uses a USB to Ethernet adapter. There is no DHCP so static IP addresses are used on host 192.168.1.2 and target 192.168.1.3.

Matlab version is R2020b.

UDP comms from host to target works fine. However, the host does not receive any of the messages sent by the target.

I have tried the usual Firewall fixes of disabling the Firewall and adding custom UDP Port rules but none of these made any difference.

I have run a different model in PIL mode using TCP with the same static IP addresses and that works fine.

Is there anything obvious that I am missing or not setting up that is stopping the host seeing the UDP messages?

[Mike Bardill]

VPN client issue. Needed a different variant of the VPN client to allow the UDP comms to get through to the host.

Answer 1

[Dhruv]

Hi Mike,

Given your setup and the issue description, it seems you have covered basic network configurations. Since UDP comms work from host to target but not vice versa, consider these steps:

1. Subnet Mask: Ensure both host and target have the correct subnet mask, typically 255.255.255.0 for a 192.168.1.x network.
2. UDP Port Configuration: Verify that the target's UDP Send block is configured to send to the correct port number that the host's UDP Receive block is listening on.
3. Network Tools: Use a network tool like Wireshark on the host to check if UDP packets from the target are arriving but not being processed or if they are not arriving at all.
4. Ethernet Adapter Settings: Check the USB to Ethernet adapter's settings on the host to ensure it's configured to allow UDP traffic on the expected port.

These steps can help isolate whether the issue is with network configuration, software settings, or hardware limitations.

[Mike Bardill]

Hi, thanks for the suggestions. The question is from quite a while back. It turned out to be something to do with the VPN we were using that was blocking the host from receiving the UDP comms. Our IT dept had to install some different variant of the VPN client and that allowed the comms to work.