Saia-Burgess Controls AG
User Manual Standby System
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Document 27-645
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Edition E
NG 02
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2017-04-26
Programming
Diagnostic
2-26
2
Forcing a switch-over using S-Bug
To test the switch-over, you can connect to the Active CPU1 with S-Bug, do a
“Stop” command, then “Instruction HALT”. This Halts the Active CPU1 and the
Standby CPU becomes Active. Note that the Standby CPU does not become Ac-
tive when the Active CPU goes into Stop - this is because you would not be able
to debug a program on the Active CPU1 without it causing a switch-over. (If the
Active CPU1 ever fails, it will always go into HALT and cause a switch-over.)
2.6.3
Switchover XOB 31
XOB 31, if present, is executed on CPU1 when the Standby PCD takes over con-
trol of the system and becomes the Active PCD.
2.6.4
System Symbols
Each of the three redundancy devices has the following diagnostic System Sym-
bols which can be used in the program. After the first build of the program, you can
find the symbols on the “System” tab of the Symbol Editor. See the Diagnostics
section for more details.
The T668 RIOs also have diagnostic symbols, see
.
Defining your own absolute addresses for diagnostic media
By default, the diagnostic Flag and Register symbols have dynamic addresses
(defined by the system), but you can assign your own fixed base addresses by
defining these symbols in a global symbol file, for example called “BaseAddresses.
src” :