If no regulation module is active the Q(t), W(t), Z(t), and L(t) laws are normally read in the (.SIR) file.

Contrary to the 2.1version, the regulation module of the 3.1 version has the priority on the .SIR file. Thus, if the regulation module controls some nodes or singular sections, the Q(t), W(t), Z(t), and L(t) laws of the (.SIR) file will be ignored.

Before beginning a hydraulic calculation, the subroutine LUSERn (n = 1 to 9) is called to read regulation parameters in the (.REG) file. At each calculation time step, before the double sweep, the SUSERns and CUSERns subroutines are called to calculate cross structures openings, manipulations at offtakes to the values and the downstream Z(t) if necessary.

In case of several regulation modules manipulating several times the same control variable U, only the latest one will have an effect in modifying U. Beware of that, for example, if you use a PRINT and PID controller for respecting printing and using a PID module. They should be defined in this order otherwise the PID will have no effect (since it will be the PRINT the latest one, and a PRINT module does not change the value of a U).