In order to be able to search for embedded Linux devices in your local network with the ADDP protocol using broadcasts/multicasts you need to add the "addpd" to your root file system.
This can be done in Digi Embedded Linux ESP in a rootfs project just by adding application "ADDP" in the project configuration page. This will also automatically launch the "addpd" on startup during runtime. You can check it is running on the embedded device with "ps". You also will see addp entries in /var/log/messages about received discovery requests.
However discovery will not work out of the box, since on the embedded Linux device you will need to add some routes to enable the broadcast messages to be received and sent by ADDPd.
To add those routes modify /etc/init.d/S81addpd.sh by adding for example:
# route add -net 220.127.116.11 netmask 240.0.0.0 dev eth0
# route add default dev eth0
such that your routeing table will look similar to:
Destination Gateway Genmask ..
192.168.42.0 * 255.255.255.0 U 0 0 0 eth0
18.104.22.168 * 240.0.0.0 U 0 0 0 eth0
default * 0.0.0.0 U 0 0 0 eth0
Now you should be able to discover the device from Linux ESP->Device Options->Device Discovery.
You might also want to use a stand alone Java application which runs under Linux and Windows.
Make sure the firewall on the PC running the device discovery tool allows UDP broadcasts/multicasts or is switched off, see also http://www.digi.com/support/kbase/kbaseresultdetl?id=838
Actually this is ok to determine the IP address you device has got in a DHCP subnet.
You also can discover devices with fixed IP and change them to DHCP through the device discovery tool (DDT).
You will not be able to change the static IP address to a different one through the DDT.
If your device has got no IP address at all (e.g. missing DHCP server) it will not reply to the recovery broadcasts, although it received the discovery request (see /var/log/messages).