Siemens SINUMERIK 840D sl Commissioning Manual page 816

Configuring the system
2.3 Configuration file "basesys.ini"
SyncModeDHCPD_SysNet
If this variable is not set on "OFF" then the DHCP servers synchronize themselves in the
system network (X120) so that only one of them actively assigns addresses. This makes it
possible to operate multiple NCUs or PCUs concurrently without having to adjust the network
settings.
Value:
Default:
The DHCP servers that are not active go into "standby" mode; in this mode they regularly get
the current address data and TCU data from the active server so that if the active server fails
a standby server can take over the active role without data loss.
● With the ON_MASTER setting instead of ON_HIGH you can influence the
● The ON_LOW setting assigns the DHCP server a lower priority than normal. It then
Note
Compatibility with earlier versions
The priority level "ON_LOW" is used automatically if the DHCP server is switched off.
Although such an NCU does have a (standby) DHCP server and keeps a backup of the
lease data, normally, however, it does not become an active server.
InternalDynRangeStart
With the two variables InternalDynRangeStart and InternalDynRangeEnd, you can explicitly
specify the range of IP address assigned by the DHCP server. The number band of the
presetting should normally suffice.
Value:
Default:
InternalDynRangeEnd
Value:
Default:
20
ON_MASTER, ON_HIGH (= ON), ON_LOW, or OFF
ON_HIGH
synchronization in such a manner that the server with the "Master" setting is always the
active server (for this it must be active on the network). This means that in the normal
situation deterministically the same controller is always the DHCP server and you can find
the actual address data (/var/etc/udhcp-eth0.leases) and the TCU data
/user/common/tcu/etc.) there. ON_MASTER should only be set for a single DHCP server
in the system network; there should not be multiple masters.
becomes the active server if no server with ON_HIGH or ON_MASTER is found in the
network.
IP address
First address in the system network + 10 or +2 (if ≤ 16 addresses)
IP address
Last address in the system network - 15 or -1 (if ≤ 16 addresses)
Commissioning Manual, 03/2013, 6FC5397-1DP40-3BA1
NCU operating system (IM7)