Delta AH500 - Additional Remarks on Special Auxiliary Relays and Special Data Registers

AH500 Programming Manual
2-82
Limited
to
Special data register Refresh time
PLC.
SR1304~SR1305
The register is refreshed when the parameter is downloaded to the
PLC, or when the PLC is supplied with power.
SR1306~SR1315
The register is refreshed when the parameter is downloaded to the
PLC.
SR1316~SR1320
The register is refreshed when the parameter is downloaded to the
PLC, or when the PLC is supplied with power.
SR1329~SR1334
Users set the value and clear it.
AH5×0
SR1335~SR1336
The register is refreshed every scan cycle when the PLC Link is
enabled.
AH5×1
Modbus connection cycle of COM1
SR1337~SR1787
Users set the value and clear it.
SR1792~SR2559
The register is refreshed every scan cycle.
SR2560~SR2659
The register is refreshed whenever an error occurs.
Note: The models AH5×0 and AH5×1 shown in the column of “Limited to” refer to
AHCPU500/510/520/530 and AHCPU501/511/521/531 respectively.
2.2.16 Additional Remarks on Special Auxiliary Relays and
Special Data Registers
1. The scan timeout timer
 SM8/SR8
When a scan timeout occurs during the execution of the program, the error LED indicator on
the PLC is ON all the time, and SM8 is ON.
The content of SR8 is the step address at which the watchdog timer is ON.
2. Clearing the warning light
 SM22
If SM22 is ON, the error log and the warning light will be cleared.
3. The real-time clock
 SM220, SR220~SR226, and SR391~SR397
SM220: Calibrating the real-time clock within ±30 seconds
When SM220 is switched from OFF to ON, the real-time clock is calibrated.
If the value of the second in the real-time clock is within the range between 0 and
29, the value of the minute is fixed, and the value of the second is cleared to zero.
If the value of the second in the real-time clock is within the range between 30 and
59, the value of the minute increases by one, and the value of the second is cleared
to zero.
The corresponding functions and values of SR220~SR226 and SR391~SR397 are as
follows.
Device
Function Value
Binary-coded
decimal system
Decimal
system
SR220
SR391
Year
00~99 (A.D.)
SR221
SR392
Month
1~12
SR222
SR393
Day
1~31
SR223
SR394
Hour
0~23
SR224
SR395
Minute
0~59
SR225
SR396
Second
0~59
SR226
SR397
Week
1~7
SR391~SR397 correspond to SR220~ SR226. The difference between SR220~ SR226 and
SR391~SR397 lies in the fact that the former adopts the binary-coded decimal while the