MATLAB: Simscape Physical Signal: Why does is exist

Question

What is the added value of simscape physical signals compared to normal simulink signals? As far as I can see, from a functional perspective there is no difference between the two types of signals: I can add units to both types, they both have a direction of flow, and they both have similar function blocks like adding, substracting… Only for physical signals the available types of blocks is very limited. Why didn't the matlab guys just use normal simulink lines instead of the physical signals?

Answer 1

Simulink signals are causal signals with a sampling rates. Simscape physical signals are variables with time derivatives. These are two different objects, although they serve the same purpose. Because of the way Simscape simulates physical systems it is not possible to directly mix Simulink signals with the Simscape variables.