Simulink: How to resolve “Invalid setting for output port dimensions of '*/Bus Creator'. The dimensions are being set to 1.” error

Question

I'm running into the following issue in a simulink model (R2012b, 64bit):

• in a subsystem, three scalar signals enter a bus creator

• the output of the bus creator is connected to one of the subsystem's output ports. The size of the output port is set to -1, i.e. inherits its size from the incoming signal

• The subsystem is embedded in another subsystem

• When the model is executed, the following error message appears:

Invalid setting for output port dimensions of 'lonsys/A\C 1 DOF/Simple longitudinal attitude system/Bus Creator'. The dimensions are being set to 1. This is not valid because the total number of input and output elements are not the same

From looking at the bus creator that raises the error, it is not at all clear what is going wrong.

Ideas?

Answer 1

As it turns out, the blocks the error message points at are not necessarily those causing the problem.

In this case, the input port of another subsystem that is connected to the output port of the subsystem containing the bus generator had a signal size set to one, colliding with the bus size of 3{3}.

In conclusion, to figure out the cause of this particular error, checking signal and port size definition upstream of the problematic block helps.