Hi Leonardo,
You can more information about these variables from this documentation page. As an overview: ssMethodType enables you to execute code for Simulink Subsystem block methods such as initialization and computation steps. The generated code executes the associated CASE statement based on the value passed in for this argument. The CASE statement block is where the logical flow of your chart, internal states and state transitions are implemented.
The values of SS_INITIALIZE and SS_STEP are usually defined at the bottom of the generated PLC code. The Chart_IN_NO_ACTIVE_CHILD is usually a variable that denotes that the chart has no active internal states. This is the initial value for is_c3_Chart. The is_c3_chart variable will change values as we transition from one internal state to other. All the internal states have distinct values assigned to them. As an example:
VAR_GLOBAL CONSTANT
Chart_IN_NO_ACTIVE_CHILD: USINT := 0;
Chart_IN_Seeking: USINT := 1;
Chart_IN_Seeking2: USINT := 2;
Chart_IN_Tracking: USINT := 3;
Chart_IN_Waiting: USINT := 4;
SS_INITIALIZE: SINT := 0;
SS_STEP: SINT := 1;
END_VAR
In this case, I have states which are internal to the chart I generated PLC code for(see attched screenshot of chart). These states are namely: Seeking, Seeking2, Tracking, Waiting and hence the corresponding variables in the Structured Text generated by the Coder. The is_c3_Chart variable switches values between these variables according to the transition conditions and logic implemented in the Chart.
