P5501 represents the bus commanded 'Acceleration time 2'. The default value for 355s is 2205 (P2205 of the ACS355)
See EN_FDNA_01_UM_G_A4 User Manual/ Page Start-up 49
The exchanged data packet size is determined by the chosen 'Drive Profile'.
Presuming you are using the 'ODVA' profile, P5106 setting establishes the Output Instance identifier and P5108 establishes the Input instance one.
For the 'minimum' required interface 'Basic speed control assembly' (2 Words Write + 2 Words Read= 8 Bytes) P5106 should be set at '20' and P5108 should be set at '70'.
For ' minimum' 'Extended speed control assembly' P5106= 21 and P5108=71
For 6 OUTs and 6 INs (24 Bytes) P5106=22/23 and P5108=72/73
...and so on.
It's all in the manual under the 'Assembly objects' bookmark.
Again, this needs to satisfy your application's needs and configured identically within the VFD, DNet Scanlist and PLC controller interface.