The resolver of a Danfoss PMSM motor can be connected to an EC-C inverter with a shielded, twisted pair cable with a minimum of 6 leads (3 twisted pairs).
Always connect the _N and _P signals of each function (sine, cosine, excitation) as a twisted pair. The shield of the cable should be connected to the chassis ground on both ends of the cable.
If the resolver signal is not working, please check that the wiring has been connected as pictured above. The shield should be connected from both ends of the cable, but for troubleshooting purposes you can try to disconnect the shield from one end of the cable to see if the issues in the resolver signal are reduced or corrected. This is usually a sign of missing or inadequate grounding of the motor and/or inverter, please refer to the article General grounding (earthing) guidelines for information about correct grounding of the devices.