Siemens SINUMERIK 840DE sl Commissioning Manual page 405

17.6.2.5 The TCU cannot establish a network connection to the assigned PCU
Error
The PCU does not have the IP address specified in the configuration, but an address from the IP range of the system network
that can be dynamically allocated. In this error case, the TCU cannot reach its configured PCU for display.
SINUMERIK Operate (IM9)
Commissioning Manual, 12/2017, 6FC5397-1DP40-6BA1
Possible error causes and remedies
Error cause 1
IP address assigned twice
The PCU has a default IP address which is also configured for another NCU/PCU. This means
that an IP address has been assigned twice and therefore there is a system configuration error.
The PCU is not an active DHCP server (otherwise, it would have the required IP), however, it
is operated in the synchronizing DHCP mode. As the address requested from the PCU has
already been assigned, the PCU is allocated an address from the dynamic address range via
DHCP.
Remedy
A decision has to be made which computer should keep the IP address that has been assigned
twice. If it is the PCU, then
● on the PCU, under network settings, this address should be again set as fixed IP address
in the system network,
● at the NCU/PCU which runs in the DHCP synchronization mode ON_MASTER, a 'Clear
DHCP' should be executed (for an NCU sc command sc clear dhcp –X120, for a PCU using
the "System Network Center" program).
● at the computer, which uses the IP address assigned twice as second computer, the IP
address should be re-configured. Notice: If this is a PCU, then it should be linked to this new
address using the "System Network Center" program (this is the first screen in the
program).
If the PCU is to change its address, then on the PCU
● under network settings, the new address should be set as fixed IP address in the system
network,
● linked to this new address using the "System Network Center" program (first screen in the
program)
● at the NCU/PCU, which runs in the DHCP synchronization mode ON_MASTER, a 'Clear
DHCP' should be executed (for an NCU using the sc command, for a PCU, using the "System
Network Center" program).
Restart the system.
Error cause 2
This was preceded by replacing the PCU hardware.
As a result of the hardware replacement, in spite of the same settings of the new PCU, the
requested (set) IP address is still internally reserved for the previous hardware as this is an
inherent feature of the system. The PCU is either active or non-active DHCP server, however,
is operated in the synchronizing DHCP mode. As the address requested from the PCU is still
reserved, the PCU is allocated an address from the dynamic address range via DHCP.
Remedy
Configuring the network
17.6 Station-related network diagnostics
391