I can confirm that the RS232 port does indeed work and provides console access. Levels are 3.3v. Use a USB-to-RS232 TTL 3.3v adapter. RS232 pinout on the board is:
1. 3.3vdc (not needed)
2. Rx
3. Tx
4. Gnd (nearest the screw hole)
I use Putty for serial usb access with the following settings.
baud rate= 115,200
stop bits=1
parity=none
flow control=none
Here's the beginning of the tty console session for a DS-2032-I that I have.
U-Boot 1.3.4-100728 (Nov 11 2014 - 13:58:34)
ARM Clock: 480MHz
DDR Clock: 336MHz
Hit Ctrl+u to stop autoboot: 2
Hit Ctrl+u to stop autoboot: 1
Hit Ctrl+u to stop autoboot: 0
|BIND err|
Unknown command:null
nand booting ...
load kernel...
load ramdisk...
init started: BusyBox v1.19.3 (2014-07-11 11:25:54 CST)
starting pid 375, tty '': '/etc/init.d/rcS'
Starting udev: [ OK ]
starting pid 606, tty '': '/sbin/iptables -A INPUT -p tcp --dport 23 -j DROP'
starting pid 607, tty '': '/sbin/iptables -A INPUT -p tcp --dport 22 -j DROP'
starting pid 608, tty '': '/sbin/iptables -A INPUT -p tcp --dport 21 -j DROP'
starting pid 609, tty '': '/sbin/inetd -f -e /etc/inetd.conf'
starting pid 610, tty '': '-/bin/sh'
BusyBox v1.19.3 (2014-07-11 11:25:54 CST) built-in shell (ash)
Enter 'help' for a list of built-in commands.
UBI device number 1, total 191 LEBs (24643584 bytes, 23.5 MiB), available 0 LEBs (0 bytes), LEB size 129024 bytes (126.0 KiB)
waiting for /dev/ubi1_0.
Check dir /dav ok! (0)
UBI device number 3, total 32 LEBs (4128768 bytes, 3.9 MiB), available 0 LEBs (0 bytes), LEB size 129024 bytes (126.0 KiB)
waiting for /dev/ubi3_0.
Check dir /davinci ok! (0)
UBI device number 4, total 31 LEBs (3999744 bytes, 3.8 MiB), available 0 LEBs (0 bytes), LEB size 129024 bytes (126.0 KiB)
waiting for /dev/ubi4_0.
Check dir /config ok! (0)
Hit Ctrl+c to stop and exec /home/initrun.sh to continue
--------------------------
Lots of cool access via the console.
Cheers,
Doug