Mitsubishi Electric MELSEC iQ-R Series User Manual page 406

Data capacity for tracking transfer
Up to 1M words of device/label data can be transferred in one scan. Set the tracking data capacity within 1M words.
If the data capacity exceeds 1M words, global devices, local devices, global labels, local labels, and module labels (extension
base unit) are not transferred in the scan. In this case, check which tracking trigger turned on in the event history of the
engineering tool and set the tracking data capacity within 1M words.
ON
Block 1 tracking trigger
OFF
ON
Block 2 tracking trigger
OFF
ON
Block 3 tracking trigger
OFF
No.1
Tracking data
Even though the size of the tracking data to be transferred is 1M words or less, the size of the data may become larger than
1M words depending on the label type or data type to be used after the data or all the data is converted with the engineering
tool. When configuring "Tracking Setting" with the CPU parameter, click the [Size Calculation] button in "Detailed setting" of
"Device/Label Detailed Setting" to check if the size of the tracking data is 1M words or less and transferred in one scan. (
Page 398 Detailed setting)
To reduce the size of the tracking data, consider the following.
• Exclude devices/labels that are not required to continue the system operation.
• Divide the tracking data into multiple blocks to transfer the data in multiple scans.
When data is different between the control system and the standby system
Store the same program, FB file, CPU parameter, and global label setting file in the CPU module of the control system and the
CPU module of the standby system for tracking transfer. ( Page 405 Memory Copy from Control System to Standby
System)
If there is any difference, only global devices (except step relay (S)), system data, and PID control instruction information are
transferred.
When the communication load from an external device via the other system is high
When the communication load from an external device via the other system (such as MELSOFT connection and SLMP
communications) is high, the load is imposed on the tracking transfer and an error may occur. In such case, review and
correct the communication path so that communication from an external device does not go through the other system or
reduce the communication load from the external device.
When the redundant function module restarts
The redundant function module can be temporarily affected by noise, and it can cause an unintended restart of the redundant
function module and an error occurs. In this case, clear the error. ( Page 208 Error Clear)
To check whether the redundant function module has restarted, check the event history. ( Page 633 Event List)
26 REDUNDANT FUNCTION
404
26.3 Tracking Transfer
n scan n+1 scan
No.1 No.1
1M words
No.2
No.3
No.3
Tracking capacity exceeded
n+2 scan n+3 scan
No.1
No.2