G-RAID with Thunderbolt 3 does not power down when mac sleeps

G-Technology G-RAID & G-DOCK
1

I use a G-RAID with Thunderbolt 3 12TB and a WD MyBook Raid on the same Cable. If I send the iMac to sleep, the MyBook drive powers down - but not the G-Tech Raid. Can I manage this by software?