Mitsubishi Electric MELSEC iQ-R Series User Manual page 52

Precautions
■Tracking
• Of all link refresh target devices (B, W) of link devices (LB, LW), tracking needs to be set for the devices in the own station
send range.
• Tracking cannot be set for link direct devices.
• Do not set tracking for the link special relay areas (SB0020 to SB01FF), which are turned on/off by the system, or the link
special register areas (SW0020 to SW01FF), where data is stored by the system.
• When setting link devices (LX, LY), do not set the refresh target device for the link input (LX) from tracking setting
(redundant settings on the CPU parameter side). When the link input (LX) changes after system switching occurs, a data
conflict occurs in the tracking transfer and the send data from the I/O master station.
For details on tracking transfer, refer to the following.
 MELSEC iQ-R CPU Module User's Manual (Application)
■Programming
In the RJ71LP21-25, the network detects a temporary communication error based on the condition of power-on/off, cables,
noise, and others. Create a program using the RJ71LP21-25 in such a way that control operation is not stopped even if such
a temporary communication error is detected. ( Page 79 Precautions for Programming)
■Detection of an error when another station is powered on/off
When either of the following operations is performed, a temporary data link error may be detected and a system switching
request may be issued.
• Another station (including the standby system) is powered on/off.
• A personal computer equipped with a MELSECNET/H interface board boots or shuts down.
If the above system switching request is issued before the standby system starts up, the control system CPU module may
detect a continuation error (system switching error). Even in this case, the control system continues to control the system
normally. Create a program where control operation is not stopped due to error detection.
Before clearing the continuation error (system switching error) detected by the control system CPU module, check that the
standby system and the RJ71LP21-25s operate correctly with the special register. ( MELSEC iQ-R CPU Module User's
Manual (Application))
1 FUNCTIONS
50
1.5 Redundant System Function