Hmmm, the instructions with that "multi-purpose" cable sound fairly complicated.
For my 9024D-M, I just plugged a standard everyday cat 5e ethernet cable into the front ethernet port (next to "I2C" DB9 connector), and plugged the other end into the 24 port 1GbE switch I've got all my lab hooked up to.
From there, I was able to ping 192.168.1.2 perfectly fine, connect to it with telnet, and connect to it with a web browser (http, tcp port 80).
Note, my (cheapo TP-LINK) 24 port switch is one of the MDI/MDIX sensing ones, so it automatically detects whether the cable plugged in is a cross over one or not and works fine either way. Most modern switches (last few years) are the same.
With nmap, try it like this:
$ sudo nmap -v -O 192.168.2.0/24
Starting Nmap 6.25 ( http://nmap.org ) at 2013-06-21 23:47 BST
Initiating ARP Ping Scan at 23:47
Scanning 68 hosts [1 port/host]
Completed ARP Ping Scan at 23:47, 0.89s elapsed (68 total hosts)
Initiating Parallel DNS resolution of 68 hosts. at 23:47
Completed Parallel DNS resolution of 68 hosts. at 23:47, 0.00s elapsed
Nmap scan report for 192.168.2.0 [host down]
Nmap scan report for 192.168.2.1 [host down]
Nmap scan report for 192.168.2.3 [host down]
Nmap scan report for 192.168.2.4 [host down]
Nmap scan report for 192.168.2.5 [host down]
Nmap scan report for 192.168.2.6 [host down]
Nmap scan report for 192.168.2.7 [host down]
Nmap scan report for 192.168.2.8 [host down]
Nmap scan report for 192.168.2.9 [host down]
Nmap scan report for 192.168.2.10 [host down]
[etc]
I don't have to specify an interface when I run it (from my OSX desktop), because my desktop's default IP route goes to the 24 port switch mentioned, which that front cable on the 9024D-M is connected to.
Does this help?
(note - edited for typo fixes)