Constants

Constants are a type of data point that represents the values that are needed in the equations of your model.

Unlike inputs - which are expected to change often - constants are expected to remain quite static and not change frequently.

If you're ever considering adding a number to one of your equations that represents something real-world (such as the maximum speed limit of your machines, the weight of your product etc.), it's better to define it as a constant, because then you can adjust it if it's ever required in the future.

Note that the above rule doesn't apply to universal constants that are guaranteed to never change - like the value of PI, or the constant used in the exponential function. You can put those numbers directly into your equations.

Inputs are very similar to constants, but they are usually much more dynamic. They can also be connected to live data, or values from other models.

Constant values are available (and often writable) from OPC-UA.