Chapter 4. PROFINET System Operation
GFK-2571N
May 2018
91
4.2.2
Duplicate PROFINET IO-Controller IP Address
The PROFINET IO-Controller detects that a network device has the same IP Address as its own
➢
during power-up,
➢
whenever a new hardware configuration is downloaded from the programmer, and
➢
during operation whenever a device with a conflicting IP Address announces its presence
6
on the
network.
When a duplicate is detected during power-up, following a reset, or following storage of a new hardware
configuration, the PROFINET IO-Controller:
•
logs a Duplicate IP Address Detected fault for itself,
•
does not connect to any configured PROFINET IO Devices,
•
periodically queries the network for resolution of the IP Address conflict.
When a duplicate IP Address is detected after the PROFINET IO-Controller has established connection to
configured IO-Devices, the PROFINET IO-Controller:
•
logs a Duplicate IP Address Detected fault for itself,
•
maintains all IO-Device connections
•
Note that whenever a second PROFINET Controller with an identical IP Address to the active
PROFINET Controller is connected to the network, the second controller will not succeed in entering
the network.
When the IP conflict is resolved, the PROFINET IO-Controller:
•
logs a Duplicate IP Address Resolved fault for itself,
•
attempts to re-connect all configured PROFINET IO-Devices,
•
logs an
Addition of Device
fault for each connected PROFINET IO-Device to indicate that device is back
online.
Note:
Power cycling a rack that has a PNC001 with the same IP Address as another node on the network will
result in two
Duplicate IP Address Detected
faults in the I/O Fault Table. This is normal behavior that
occurs because the PROFINET Controller retains IP parameters through a power cycle and attempts to
exist on the network before receiving a new configuration from the CPU. The first fault occurs before
the PNC001 receives the new configuration and the second fault occurs after the PNC001 receives its
new configuration. Both faults result in the PNC001 not attempting to connect to the network.
4.2.3
Resolving Duplicate IP Addresses
Whenever an IP Address conflict exists, IP-based network communication with the device(s) may be disrupted.
The IP Address conflict should be resolved by disconnecting one of the offending devices from the network or
assigning each a unique address. The
Duplicate IP Address Detected
fault lists the MAC address of the offending
devices in bytes 8
–
13 and 14
–
19 of the Fault Extra Data. The
Discovery and Configuration Protocol
(DCP) tool
in Proficy Machine Edition may be useful to identify PROFINET devices on the network with conflicting IP
Addresses.
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The PROFINET Controller uses the ARP protocol to detect duplicate IP addresses. Devices that issue a gratuitous ARP to
announce their presence on the network are detected.
