c3dbfd83_imply_Modbus___Exception_Codes__Meaning
[Exception Code] 07 (07 hex) [Name] Negative Acknowledge [Meaning] 
The slave cannot perform the program function received in the query. This code is returned for an unsuccessful programming request using function code 13 or 14 decimal. The master should request diagnostic or error information from the slave.
Simply Modbus - Exception Codes
Meaning