Technical data

143
W&T
Subject to errors and modifications
To ensure that the Web-IO can be accessed even if the DHCP/
BOOTP server goes down, the previous IP address is retained
when there is no response.
!
In DHCP environments the IP address to be assigned
must be reserved by means of a fixed connection to the
Ethernet address of the Web-IO. Under Windows NT this
is done in the DHCP manager under „Reservations“. Linux
provides the file „dhcpd.conf“ for this purpose; where you need
to make a corresponding entry.
!
If you change this option in the Web configuration, the
change to the checkbox is not updated until after a
device reset.
7.1.2 ... using ARP command
The prerequisite is a PC which is located in the same network
segment as the Web-IO and on which TCP/IP protocol is
installed. Read the MAC address for the device from the label
(e.g. EN=00C03D0012FF). Under Windows you first ping
another network client and then use the command line
described below to insert a static entry into the computer‘s ARP
table:
arp -s <IP-Adresse> <MAC-Adresse>
e.g. under Windows:
arp -s 172.0.0.10 00-C0-3D-00-12-FF
e.g. under SCO UNIX:
arp -s 172.0.0.10 00:C0:3D:00:12:FF
Now ping the device again (in our example you would ping
172.0.0.10). The IP address is not stored in the non-volatile
memory.
!
This method is only usable if no IP address has yet been
assigned to the Web-IO, i.e. the entry ius 0.0.0.0. To
change an already existing IP address you must use the
configuration menu from your browser or use WuTility.