I understand that you are trying to write to a Data Store Memory using C action language.
In order to achieve this in "Chart(C)", you can index into the array as follows:
MyData.buffer[0][0] = 1;
C action language follows zero based indexing as opposed to MATLAB action language that follows one based indexing. You can refer to the link below for further information about how to modify the action language of a chart:
You can also refer to the following link that lists the differences between MATLAB and C as Stateflow action language syntax:
Hope this helps!
