Precautions For Network Configuration Including A Redundant System - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

7 APPLICATION FUNCTIONS

7.10.2 Precautions for network configuration including a redundant system

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This section describes precautions when configuring a MELSECNET/H or
MELSECNET/10 network including a redundant system.
When configuring such a network, pay careful attentions to the following points.
For details, refer to (1) and (2) of this section.
1) Use a network module of function version D or later for the following:
● Network module to be mounted on the same base with the redundant CPU
● Network module to be mounted on the same base with a QCPU other than the
redundant CPU and used as a control station
2) Use GX Developer of version 8.18U or later for the following stations, and set
network parameters:
● Network module to be mounted on the same base with the redundant CPU
● Network module to be mounted on the same base with a QCPU other than the
redundant CPU and used as a control station
3) The network module mounted with an AnUCPU or QnACPU cannot be set as a
control station if a redundant system using Q4ARCPUs or if redundant CPUs exist
*3
in the network .
4) When the redundant system is in the debug mode, do not connect the network
modules on both systems to the network at the same time. In the debug mode,
system B CPU also operates with the same parameters as system A. Therefore,
duplication of the control station is detected at the time of concurrent connection
to the network
5) The following operations must be performed prior to system operation.
● Power ON/OFF of other stations (including stations on the standby system)
● Startup and shutdown of the personal computer where a MELSECNET/H
interface board is installed
If the above operation is performed during system operation, a MELSECNET/H
module on the control system may detect a communication error and a system-
switching request may be issued.
When the system-switching request is issued before startup of the standby
system, a continue error, "CAN'T SWITCH" may be detected in the control
system CPU.
Generally, normal system control is continued even if "CAN'T SWITCH" is
detected. However, in the case of the system where error detection will stop the
control, program the system to prevent such a control stop.
For the method for automatically clearing the "CAN'T SWITCH" error, refer to the
QnPRHCPU User's Manual (Redundant System).
*1: When the redundant CPU is in debug mode, a network module of function
version A or B can be used.
*2: When the redundant CPU is in debug mode, GX Developer compatible with
each QCPU can be used.
*3: When the Q4ARCPU is used in a single CPU system or when the redundant
CPU is in debug mode, the network module mounted with an AnUCPU or
QnACPU can be set as a control station.
MELSEC-Q
*1
*2
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