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SIMATIC 545/555/575 System Manual
Installing 575 System Hardware
If a 575 CPU is not in slot 1, then the system controller is responsible for
informing the primary 575 CPU about battery status. The system controller
writes a 255 (FF
16
), for battery good, or 0, for battery bad, to the battery
status
(BATGOOD) location at BASE-ADDRESS+4, where BASE-ADDRESS is the
base address of the 575 system tables. (Refer to Section 4.11 of this chapter
for additional information on
BASE-ADDRESS.) This variable is an 8-bit
integer (byte). For information about the 575 CPU’s system tables, refer to
SIMATIC 575 Interboard Communication Specification (PPX:575–8103–x).
Each 575 CPU uses one megabyte of VMEbus A24 memory space and 16
bytes of A16 memory space. Additionally, each 575 VMEbus I/O module uses
two bytes of A16 memory space and 64 Kbytes of A24 memory space.
Table 4-6 shows how each function uses memory.
Battery Status
Using VMEbus
Address Space
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