hi Hillmann,
I sometimes had to prepare a Duple or Elite for a DIN rail mounting. I ordered "DIN rail holder TSH 35" from Bopla (Product no. 22035000).
This adapter is – amongst others – available from:
Farnell / Newark (order code 4189991)
Conrad (order code 539775 – 89)
Distrelec (order code 300060)
Then I drilled 2 holes of 2,4mm diameter in the bottom of the Duple and tapped a M3 thread in them. Then mount the holder with short M3 bolts so they don't touch the PCB inside the box.
I have attached an image of the result.
best regards,
Maarten