Sorry for necroposting, but for folks using Linux or other nicely scriptable shells, here's the script I use for screenshots on the DS2000 series:
#!/bin/sh
echo ":DISPLAY:DATA?" | nc -q 1 IP_ADDRESS 5555 | tail -c +12 | head -c -1 | bmptopnm 2> /dev/null | convert ppm:- $1
Only requires fairly standard tools like ImageMagick to be installed. If you write that to a file called "oscshot", then you can run a command like this:
$ oscshot screencap.png
Obviously it's marginal how useful this is when you only have one thing to capture when there's tool like the one from Fire Doger. I mean, for me personally it's much faster to just pull the command out of my command history than to click buttons all over the place, but that's just me. But my little script above becomes really cool when you write scripts which turn on/off your power supply, producing sequences of images across ranges of input voltages, etc.