Sampling Methods Of Devices And Labels - Mitsubishi Electric MELSEC iQ-R Series User Manual

Sampling methods of devices and labels

The following table shows the sampling methods of devices and labels.
Sampling method
Each scan
Time specification
Trigger instruction
Safety cycle time
When sampling a device and label in a periodic execution type program, an interrupt program, or a safety
program, the program may be executed during data sampling if "Each Scan" or "Time Specification" is
specified for the sampling method. In this case, inconsistency of sampled data occurs.
To avoid data inconsistency, configure a new setting with another setting number as follows:
• Periodic execution type program or interrupt program: Specify "Trigger Instruction" for the sampling method
and set a device and label used in a periodic execution type program or an interrupt program as a sampling
target. In addition, execute the DATATRG instruction immediately before the END processing.
• Safety program: Specify "Safety Cycle Time" for the sampling method and set a device and label used in a
safety program as a sampling target.
Precautions
When selecting "Recording Startup Trigger + File Saving Trigger" for the recording method, data is accumulated for a
specified period after a recording startup trigger is satisfied. Therefore, no data is accumulated if the sampling timing is out of
the specified period.
Sampling timing when selecting "Each Scan"
The sampling timing is as follows:
(a) (1)
(1) I/O refresh
(2) Program operation
(3) END processing
*1*2
(4) Sampling processing
(5) Scan time
(6) Time
(a) Scan execution program
*1 The time required for sampling processing is added to the scan time. For details on the sampling time, refer to the following:
Page 296 Sampling time
*2 If an interrupt program is executed during the END processing, the execution time of the interrupt program is also included in the
sampling time.
1 FUNCTIONS
44
1.1 Recording Function
Description
Data is sampled during the END processing in a scan of a CPU module.
Data is sampled during the END processing in a scan executed first after a specified time elapses.
Data is sampled when executing the DATATRG instruction.
Data in a safety program and safety FB is sampled at the end of safety cycle processing.
(2) (3) (1)
(4)
(5)
(2) (3) (1)
(4)
(5)
(2) (3) (1)
(4)
(5)
(2)
(6)