Hitachi SJ Series, User Manual

Page: 501 / 786

14-10
Chapter 14 RS485 Communication
14.3.6 Time required for communication
• The inverter’s response after it receives a query is equal
to [CF-07] (communication waiting time) setting value
plus processing time for creating response.
14.3.7 Responses in the normal condition
• A response is returned in accordance with the format for
each query defined in “3. Description of Each Function
code”.
14.3.8 Responses in the abnormal condition
• When there is a failure (excluding communication error)
in the content of a query, the inverter returns an
exceptional response without executing any action
requested by the query.
• For error determination, check the function code of the
response. The function code of the exceptional response
is the value obtained by adding 80h to the function code
of the query.
14.3.9 No response
• The inverter ignores a query and returns no response in
the following conditions:
(1)
A broadcast (query with slave address “0”) is received.
(2) A communication error is detected during a query
reception processing.
(3)
The query’s slave address doesn’t match the slave
address set in the inverter.
(4) The time interval between data constituting a message
is 3.5 characters or less.
(5) The data of query is in the wrong length.
(6) The reception interval within frame exceeds 1.5
character.
• When transmitting the next query to the inverter after
receiving a response from the inverter, make sure to
provide an interval equal to the silent interval of [at least
3.5 characters] or more.
• Field composition for
exceptional response
• For more details of errors, see “14.3.9 Exceptional
Responses”.
(7)
An error check code of query does not match (CRC
error).
(8) A simultaneous broadcasting by group (query with
slave address from 250 to 254) is received.
• Provide the master with a timer for monitoring responses,
then if a response is not returned within the time, transmit
the same query again.
！
Slave address
Function code
Exception code
CRC-16