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Theory of IEC HSBY Operation
44
840 USE 106 00 January 2003
IEC Hot Standby Definitions
Definitions The following are IEC Hot Standby definitions.
Exec: Quantum controller operating system with integrated IEC language support
(IEC runtime system)
Program Data: A continuous memory block containing all program variables,
including:
Non-located IEC variables and constants declared in variable editor
Links in FBD and LD sections
Stack (loop) variables in IL and ST
SFC states
Literals
Pointer lists
Internal states of EFBs
DFB Instance Data: Multiple memory blocks containing:
Internal data of each DFB instance
Process diagnostics buffer
Mirror buffer: 1 Byte per configured 0x/1x reference (only Concept 2.1 and older)
Used references list: 1 Bit per configured 0x/1x reference
IEC Heap: One continuous memory block containing:
Program data
DFB instance data
Maximum IEC Heap Size: 128 KByte together with state RAM. If 10K Words (20
KByte) of state RAM are used already for I/O references the max. IEC heap size
would be 128 KByte – 20 KByte = 108 KByte
Currently used IEC Heap Size: DFB instance data plus (configured) program data
area size
State Table: Also called state RAM, controller references for both real world I/O and
internal referenced (located) variables
Project: Concept program file containing controller configuration and IEC language
control code
Application: Downloaded IEC language control code and data