Hello Franc,
I don't really understand the whole situation (I guess you are using LabVIEW... which version? which version of Diadem?)
Anyway, as a first step I recommend you to navigate here and make sure the SCXI 1112 is configured as it should and measures temperatures correctly:
http://zone.ni.com/devzone/conceptd.nsf/webmain/F5C64678D54A37358625696500648FC0?opendocument
Once this is done, you'll be able to build your datalogging application (or adapt an included example). Please take a look at LabVIEW's examples for the SCXI-1112. On the Code Library you can find examples for this SCXI module too.
In order to import the data logged into Diadem, there are 2 nice links here that might be helpful:
http://zone.ni.com/devzone/conceptd.nsf/webmain/9
C7769446E6F18B486256C4C0070FC3C?opendocument
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DCC756A4E034080020E74861&p_node=DZ52003&p_source=External
Hope this helps!