6. Redundancy with NX3030 CPU
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Overall, it can be listed up to four IPs, according to the IP change method.
Fixed IP
It’s the simplest method for IP addressing and can be configured in the Ethernet interfaces in the
NX5000 Ethernet modules. In this method, it’s only listed the IP addresses from the PLCA and from
PLCB. Apart from the redundancy state, PLC Active or Non-Active, the PLCA will always answer
by the configured IP, as also will PLCB.
Figure 6-9. Fixed IP method
Parameters that must be configured in the Fixed IP method:
IP Address PLC A: PLCA communication address
IP Address PLC B: PLCB communication address
Subnetwork Mask
Gateway Address
Exchange IP
The Exchange IP can be configured in the Ethernet interfaces in the NX5000 Ethernet module. In this
method, the half-cluster IP depends on the PLC state (Active or Non-Active). On every switchover
the IP change occurs between the half-clusters allowing them to assume the IP address from the new
redundancy state.
PS: for this addressing method, the Ethernet ports from both PLCs (PLCA and PLCB) assume the
same IP address while they both are in the Non-Active state, generating a network address conflict.
Considering this situation uncommon, where no PLC is controlling the system, this turns out to be a
big problem and has to be considered.
Figure 6-10. IP Automatic Change
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