I.R.I.S. Cardiris 5 for Microsoft Dyn CRM - Manual (Page 13)

How to configure Cardiris for Microsoft Dynamics CRM
12
When a CRM field has been mapped to a Cardiris field, the CRM field
is removed from the other drop-down lists. This means you can never
map a single CRM field to several Cardiris fields. By preventing this,
correct 1:1 field mapping is guaranteed.
Note that pictures and notes from Cardiris records are always exported
to the Notes field in CRM 3, 4 and 2011 Server and to the Notes and
Activities section in CRM Online.
Note: not all CRM fields are eligible for field mapping. Cardiris
automatically discards CRM fields that are not:
 readable
 writable
 updatable

of the Strings type

Then, at the bottom of the window, select the CRM entity type
to which Cardiris contacts are to be mapped. Cardiris contacts
can either be mapped to CRM Leads or CRM Contacts.