
Chapter 4. CPU Operation
GFK-2222AD
April 2018
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4.11.4
Retention of Data Memory Across Power Failure
The following types of data are preserved across a power cycle with an operational battery (for RX3i
CPE302, CPE305, CPE310, CPE330),CPE400 models with an operational and attached Energy Pack. RSTi-
EP CPE100/CPE115 have in built super capacitor for data retention.
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Application program
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Fault tables and other diagnostic data
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Checksums on programs and blocks
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Override data
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Data in register (%R), local register (%L), and program register (%P) memory
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Data in analog memory (%AI and %AQ)
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State of discrete inputs (%I)
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State of retentive discrete outputs (%Q)
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State of retentive discrete internals (%M)
The following types of data are not preserved across a power cycle:
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State of discrete temporary memory (%T)
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%M and %Q memories used on non-retentive -()- coils
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State of discrete system internals (system bits, fault bits, reserved bits).