System Switching Request To The Control System Cpu Module; Functions Restricted In A Redundant System - Mitsubishi Electric MELSEC iQ-R Series User Manual

System switching request to the control system CPU module

When the RJ71LP21-25 mounted on the control system detects a data link error, it issues a system switching request to the
control system CPU module.
However, depending on the operating status of the standby system, system switching is not executed.
For details on the operating status of the standby system and whether system switching is executable, refer to the following.
 MELSEC iQ-R CPU Module User's Manual (Application)
System switching cause
This section describes causes that make the RJ71LP21-25 issue a system switching request.
For details on causes other than a system switching request from the RJ71LP21-25, refer to the following.
 MELSEC iQ-R CPU Module User's Manual (Application)
■Moderate/major error and hardware failure
When detecting an error where the RJ71LP21-25 cannot continue the processing, the RJ71LP21-25 notifies the control
system CPU module about the error and issues a system switching request.
■Data link error
If the data link error status (D LINK LED off) continues for the system switching monitoring time set in "Supplementary Cyclic
Settings" under "Application Settings" or longer, the RJ71LP21-25 issues a system switching request to the control system
CPU module.
When cyclic transmission is stopped using the link start/stop of the MELSECNET diagnostics, a system
switching request is not issued to the control system CPU module. (This also applies to cyclic transmission is
stopped by the link special relay (SB) or link special register (SW).)

Functions restricted in a redundant system

The following table lists the functions restricted when the RJ71LP21-25 is used in a redundant system.
Function
Transient transmission
Restrictions
• To perform the transient transmission specifying the control system or standby system, acquire the current target station
address (address of the control system or standby system) by using the module FB RedundantSystem_GetAddress and
access the acquired address. ( MELSEC iQ-R Ethernet, CC-Link IE, and MELSECNET/H Function Block
Reference)
• Precautions exist for communications with different networks when the networks contain a redundant system.
(Page 36 When the networks contain a redundant system)
• Precautions exist for when the dedicated instructions are used to a redundant system. (Page 174 Precautions for
dedicated instructions (when used in a redundant system))
1 FUNCTIONS
1.5 Redundant System Function
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