The last checked firmware and manager for SECU-3 (at 10022015)
Currently the last checked firmware and manager are the release from 10-02-15.
The short list of modifications in comparison with previous version is available here
For users who had bought their units in 2013 or earlier – MEGA32 not supported!
There is a lot of firmware versions for every occasion. You can read their description in file release.txt
You should use the new manager (from this page or release from 10-02-15) after the firmware upgrade.
You should reset EEPROM after firmware upgrade!!!
Your parameters and settings will be lost, that is why you need to remember/note them beforehand.
Which firmware should I chose?
You can also use other versions of firmwares but only if you know their purpose. You can read their description in file release.txt