Method for testing the functional stability of a refrigerating machine

A method for testing the functional stability of a controller of a refrigerating machine wherein said controller, for which status variables are set and which has inputs for input variables and outputs for output variables, carries out control cycles which involve, in sequence, the following operations:

• A acquiring values of said input variables, which represent functional conditions of the refrigerating machine,
• B executing a control algorithm which, on the basis of the values of said input variables and of said status variables, sets values for said output variables so as to control operation of the refrigerating machine;
• C repeating operations A and B following lapsing of a control cycle time T from the start of operation A;
• said testing method involving an operation of connecting said controller to a diagnostic unit for exchanging data during the operation of said controller;
• said testing method comprising, during the operation of said refrigerating machine, a recording step (100) and a subsequent execution step (200), which are carried out by said diagnostic unit;
• wherein said recording step (100) involves in sequence:
• an operation D which is carried out following said operation B and which involves associating, with a recording cycle identifier IDR, a progressive value calculated starting from a start cycle, which is the control cycle of said controller in which said recording step (100) is started;
• an operation F of recording a set of reference data, which consists of a set of current values of said input variables, said status variables and said output variables;
• said recording step (100) further involving associating with each reference data set the recording cycle identifier IDR of the control cycle in which said reference data set was recorded;
• repeating said operation D and said operation F for each control cycle until the end of said recording step (100);
• wherein said execution step (200) involves in sequence:
• an initialization operation H in which, during the execution of said operation A, the current values received by said controller for said input variables and for said status variables are replaced by the values of said input variables and said status variables of the reference data set which was recorded in the operation F carried out in said start cycle;
• wherein the control cycle in which the operation H is performed is assumed as an initialization cycle;
• an operation I of recording an execution cycle identifier IDE which involves associating with said execution cycle identifier IDE a progressive value calculated starting from said initialization cycle;
• an operation J of recording, following operation B, a control data set, which comprises a set of current values of said output variables;
• wherein said execution step (200) also involves associating with each control data set the execution cycle identifier IDE in which said control data set was recorded;
• a write operation K, in which the values of the input variables of the reference data set which was recorded in operation F carried out in the control cycle having a recording cycle identifier IDR directly following the execution cycle identifier IDE recorded in said operation I are assigned to the values of said input variables, in such a way that, in operation A of the subsequent control cycle, the values of said input variables are those assigned in said operation F;
• repeating said operation I, said operation J and said operation K for each control cycle until the end of said execution step (200).