SoMachine v4 and onwards facilitates the graphical view of memory use for the controller.
This view lists the Total memory size, Used memory size and Free memory size for
(1) Input Area (%I)
(2) Output Area (%Q)
(4) Retain Data
(5) Persistent Data
To check this, Open SoMachine project => Go to Device Tab => Right click on MyController => Select "Device Memory Info". Device Memory Info window gets opened. Click Refresh once.
Refer to the below snap that gives idea about how "Device Memory Info" lists memory use.
This is sample view only.