Simulink If block error "Port 1 must directly or indirectly connect to one If Action Subsystem"

Hello, I am working to use an If block and If action blocks to set shift points for a vehicle model, the code that I am going after would be:

If u1 > 57.3421

6th Gear If Action Block activated

elseif u1 > 46.2345

5th Gear If Action Block activated

elseif u1 > 35.9144

4th Gear If Action Block activated

elseif u1 > 25.6962

3rd Gear If Action Block activated

elseif u1 > 4.2575

2nd Gear If Action Block activated

else

1st Gear If Action Block activated

end

but I keep recieving an error that Port 1 must be connected to an If action block. Any suggestions on how to fix this?

Attached are pictures of the example I was using to build this and the model I have created.

Answer 1

[Fangjun Jiang]

Outport 1 of the If block is also connected to another destination but it was not shown in the snapshot. Dis-connect that branch and do the same for the rest.

Outputs from the if, else, and elseif ports are action signals to If Action Subsystem blocks. They can't be connected to other places.

[John Harrison]

Thank you, I had those ports connected to other If Action subsystem blocks, but after reworking the system so one If port goes to one if Action block it worked.

[Fangjun Jiang]

The trigger signals can only be connected to one destination. That was my impression and I suspect that was the cause of your issue. But I couldn't find any statement on this from the Simulink document.

Answer 2

[Song-Hyun Ji]

You may consult the response provided in this article.

https://www.mathworks.com/matlabcentral/answers/2175743-how-to-control-multiple-if-action-subsystem-blocks-with-one-if-block