The EURO-5V is an inline DC-DC converter that generates a +5V power rail for modules that also require a +5V rail in addition to the standard +/-12V rails.
An onboard header allows the adaptor to be configured as either 'module only' or 'loopback'.
In `module only' mode the 5V is only available to the module that is connected to the adaptor.
In `loop-back' mode the 5V rail is ALSO fed back on to the busboard allowing other modules on the same busboard access to the 5V supply. In this mode only 1 adaptor should be fitted per busboard.
The module is rated to in excess of 500mA.
Power is derived from the +12V rail so you must ensure that your system power supply is suitably rated for the additional loading (typically 125mA).