Hitachi WJ200-001S Instruction Manual page 344

No response occurs:
In the cases below, the inverter ignores a query and returns no response.
 When receiving a broadcasting query
 When detecting a transmission error in reception of a query
 When the slave address set in the query is not equal to the slave address of the
inverter
 When a time interval between data elements constituting a message is shorter than
3.5 characters
 When the data length of the query is invalid
 When broadcast message received.
NOTE: Provide a timer in the master and make the master retransmit the same query
when no response is made within a preset time period after the preceding query was
sent.
B9