Why is the method rto.InputPort(1).Data wrong?

Hi.

I am trying to get the value of Display block by m scripts. I am using the following scripts learned from Access Block Data During Simulation.

obj2=get_param([model_name,'/EngineRPM'],'RuntimeObject');
obj2.InputPort(1).dataasdouble

This method can return correct answer indeed, but sometimes the result is not correct:

Why? And what should I do?

Thanks for your attention.

Answer 1

[yang xiang]

Finally I found the where the problem is, however I still do not know what's the essantial reason.

the display block "d3" shows right value in its UI, but when we try to get the value via code, it returns zero number.

this problem doesn't occur in other display blocks (and derivative blocks too), and even doesn't occur when I copy this block to other models:

It really confused me. Could someone gives me some more information?

[Walter Roberson]

That would suggest to me that the block name is possibly not 'd3' . For example it might be 'd3 '

Or perhaps there is something else in the model that has a 'd3' ?

[yang xiang]

No. I add those display blocks just for debugging. There is no any other blocks named like that, if i made a typo in the ‘d3’ block, matlab should threw a error message rather that a zero number.

[yang xiang]

I think there could exist a bug in the derivative block, because when i rebuilt the derivate block on my own, this problem disappeared.