Unfortunately that is not a supported configuration because you can't connect one raid controller module to another raid controller module.. You would need to use a MD1200 behind the MD3200.
I wonder if it is possible to connect one DELL PowerVault MD3200 as expansion to onother one DELL PowerVault MD3200. If it is possible how i could do it (cabling only?) ?
How i could connect one DELL PowerVault MD3200 as expansion to onother one DELL 
PowerVault MD3200 .