Solution : https://service.sap.com/sap/support/notes/488810 (SAP Service marketplace login required)
Key words : 
ssf_get_device_type function module exists, function module determines, code page reason, attached routine form, terms smart forms, relevant device type, smart forms, device type, application wanted, required depending
Related Notes : 
       
| 762870 | Language-dependent selection of device type | 
| 409194 | Printing from Acrobat Reader vs. Printing from SAP | 
| 323736 | Restrictions with "PDF print" through spooler |