Hitachi NES1-004SB Quick Reference Manual page 162

Chapter 8 Communication Functions
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 the reception space is more than 1.5 characters in the frame
 When an error check cord of query is incongruous (CRC error)
Note) Provide a t imer 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.
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