Omron CP1H CPU Operation Manual page 717

Auxiliary Area Allocations by Address
A300: Error Record Pointer
A501.00 to A501.15: CPU Bus Unit Restart Bits and
A302.00 to A302.15: CPU Bus Unit Initialization Flags
CPU Bus Unit Initialization Flags
Error record 1
Error record 20
Example: Unit No. 1
CPU Bus Unit Restart Bits
A501.01 (or at startup)
A302.01
00 to 14 hex
Points to the next record to be used.
Example
Stored
Stored
Stored
next
Automatically turned OFF by system.
Unit initialized.
Appendix D
683