c3dbfd83_imply_Modbus___Exception_Codes__Meaning
[Exception Code] 02 (02 hex) [Name] Illegal Data Address [Meaning] 
The data address received in the query is not an allowable address for the slave. More specifically, the combination of reference number and transfer length is invalid. For a controller with 100 registers, a request with offset 96 and length 4 would succeed, a request with offset 96 and length 5 will generate exception 02.
Simply Modbus - Exception Codes
Meaning