Theory of IEC HSBY Operation
840 USE 106 00 January 2003 45
IEC Heap The most important new terms to understand in IEC Hot Standby are the IEC Heap,
the Currently used IEC Heap Size and the Maximum IEC Heap Size.
Program Data
Area The program data area has a default size of 16 KByte whenever a new Concept
project is created. Its size may be adjusted to the amount of memory that’s really
needed for a particular application. This can be done in the Memory St atistics Dialo g
while Concept is not connected to the PLC. This dialog can be activated through
Online --> Memory Statistics.
Configure size of program data area at the Memory Statistics dial og in offlin e mod e.
The maximum size of the IEC heap is the maximum amount of memory avail able for
data in any particular IEC application. What this means in terms of IEC HSBY is
shown in the diagram in
All State RAM transferred, p.52.
Note: Changing the configured size of the program data area results in a complete
download of the application, no download changes are possible.