Now though with sleep mode!

After I was angry at first about the lack of sleep mode (iMac 2012), gabs after less than a week but still surprising message from support. Several emails later, all on the same day, I received a not yet published firmware update program by the manufacturer and recorded (Version: 101007_00_7F_04). After FW upgrade the disks go into sleep mode (spin down), as it should be.

The FW update is now available on the website. By navigating to inXtron dot com in the folder / firmware / sk3500 U3 firmware. The firmware version you need is the 101007_00_7F_04 (beta) or later.
To install the FW is a Windows computer required because the FW tool runs only on Windows. Whether it works well with a VM or Boot Camp I can not say.

Thus I am now fully satisfied with the two inXtron housings. Finally, no more disconnections or the message that the disk was not ejected when auswachen from sleep mode as was the case with the Poppstar housings. The manufacturer support is laudable, even if the initial response took 6 days to complete.