I have connected Simulink on a computer, with ROS on another one through a tcp/ip interconnection using the ROS publisher and subscriber blocks. The connection is successful and I am able to send information to ROS through the publisher block.
The problem is the only way I have received data from the subscriber block is when I read data from the same topic I am writing (with the publisher block), all the other topics give a blank message despite I have done an "echo" on the PC running ROS and they are not empty.
I selected the topic source from the ros network and also tried to specify my own. Furthermore, I used a virtual machine before testing it on two diffetent PC's and have te same issue.
I am runing Matlab 2021a on Ubuntu 16.04 and ROS Melodic on Ubuntu 18.04.