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CHAPTER12 PECIAL RELAY LIST AND SPECIAL REGISTER LIST
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12.2 SPECIAL REGISTER LIST
 
(7)  Debug
*1: The module whose first 5 digits of serial No. is "10042" or later.
(8)  Redundant CPU information (host system CPU information
*1
) 
*1: The host system CPU information is stored.
(9) Remote password count 
*1: This applies to the Built-in Ethernet port QCPU.
Table12.25 Special register
Number Name Meaning Explanation
Set by 
(When Set)
Corres-
ponding  
ACPU  
D9
Corresponding 
CPU
SD840
Debug function 
usage
Debug function 
usage
Stores the status of the debug function usage as shown below.
 0: Forced ON/OFF for external I/O
 1: Executional conditioned device test
 2 to 15:Absent (0 fix)
(0: Not used, 1: Used)
S (Status 
change)
New
QnU
*1
Table12.26 Special register
Number Name Meaning Explanation
Set by 
(When Set)
Corres-
ponding  
ACPU 
D9
Corresponding 
CPU
SD952
History of 
memory copy 
from control 
system to 
standby system
Latest status of 
memory copy 
from control 
system to standby 
system
Stores the completion status of the memory copy from control system to 
standby system executed last.
1) Stores the same value as stored into SD1596 at normal completion/
abnormal completion of the memory copy from control system to 
standby system.
2) Backed up for a power failure, this special register holds the status of 
memory copy from control system to standby system executed last.
3) Cleared to 0 by latch clear operation.
S (Status 
change)
New QnPRH
Table12.27 Special register
Number Name Meaning Explanation
Set by 
(When Set)
Corres-
ponding  
ACPU 
D9
Corresponding 
CPU
SD979
Direct 
MELSOFT
connection
Count of unlock 
processing 
failures
Stores the count of unlock processing failures.
Range: 0 to FFFEH (FFFFH when the limit is exceeded)
S(Status 
change)
New
QnU
*1
SD980 to 
SD995
Connection 
1 to 16
SD998
MELSOFT
connection 
using TCP port
SD999
FTP
communi
cation port
0
b15 b2to b1 b0
Executional conditioned 
device test
Forced ON/OFF for 
external I/O