App
- 9
Appendix 1 Special Relay List
APPENDICES
(4) Scan information
(5) I/O refresh
*1: This applies to the CPU of function version B or later.
Number
Name
Meaning
Explanation
Set by
(When Set)
Corres-
ponding
ACPU
M9
Corresponding
CPU
SM415
2n (ms) clock
• This relay alternates between ON and OFF at
intervals of the time (unit: ms) specified in SD415.
• When Programmable Controller power supply is
turned OFF or a CPU module reset is performed,
goes from OFF to start.
(Note that the ON-OFF status changes when the
designated time has elapsed during the execution of
the program.)
S (Status change)
New
Qn(H)
QnPH
QnPRH
QnU
SM420
User timing clock No.0
• Relay repeats ON/OFF switching at fixed scan
intervals.
• When Programmable Controller power supply is
turned ON or a CPU module reset is performed,
goes from OFF to start.
(For the redundant CPU, however, this relay is
always OFF after system switching.)
• The ON/OFF intervals are set with the DUTY
instruction
n1: ON scan interval
n2: OFF scan interval
S (Every END
processing)
M9020
SM421
User timing clock No.1
M9021
SM422
User timing clock No.2
M9022
SM423
User timing clock No.3
M9023
SM424
User timing clock No.4
M9024
SM430
User timing clock No.5
• For use with SM420 to SM424 low speed programs
S (Every END
processing)
New
QnA
Qn(H)
QnPH
SM431
User timing clock No.6
SM432
User timing clock No.7
SM433
User timing clock No.8
SM434
User timing clock No.9
TableApp.5 Special relay
Number
Name
Meaning
Explanation
Set by
(When Set)
Corres-
ponding
ACPU
M9
Corresponding
CPU
SM510
Low speed program
execution flag
OFF : Completed or not
executed
ON : Execution under way.
• Goes ON when low speed execution type program is
executed.
S (Every END
processing)
New
QnA
Qn(H)
QnPH
SM551
Reads module service
interval
OFF : Ignored
ON : Read
• When this relay goes from OFF to ON, the module
service interval designated by SD550 is read to
SD551 to SD552.
U
New
QnA
Qn(H)
QnPH
QnPRH
Rem
TableApp.6 Special relay
Number
Name
Meaning
Explanation
Set by
(When Set)
Corres-
ponding
ACPU
M9
Corresponding
CPU
SM580
Program to program I/
O refresh
OFF : Not refreshed
ON : Refreshed
• When this special relay is turned ON, I/O refresh is
performed after execution of the first program, and
the next program is then executed.
When a sequence program and an SFC program are
to be executed, the sequence program is executed,
I/O refresh is performed, and the SFC program is
then executed.
U
New
Q00J/Q00/Q01
*1
n(ms)
n(ms)
n1 scan
n2 scan
n2 scan
DUTY
n1
n2
SM420
