Hi,
the ESS power supply is the wee green plug/socket directly above the silver Ethernet socket. The ESS requires a good stable 5V supply of about 500mA. Don't skimp, a good quality supply
is essential. An overvoltage excursion on the power supply input will wreck an ESS...and no come backs on that sort of failure.
The ESS has three parallel port output sockets, those are the three black rectangular 26 pin IDC sockets. In the picture above only one is populated, that is to say that it has an IDC-to-DB25
adaptor cable (ribbon) that plugs into the G540 directly. In one of the earlier photos there was a second breakout board plugged into the ESS, in addition to the G540. That will allow you to
have more inputs and outputs than a G540 on its own. The ESS has with all three ports operating has 51 inputs/outputs combined.
Warp9TD make the ESS sell the IDC26 to DB25 adaptor cables for about $10.00.
Craig