Hitachi WJ C1 Series User Manual

Chapter 11 RS485 Communication
11-1-7
■ (5) Communication time required
 The response of the inverter after the inverter receives a query is as follows: "Silent interval (3.5
characters)" + "Communication wait time [C078]" + "Processing time such as response message
creation (several msec)".
 After the external control equipment receives a response from the inverter, be sure to leave an
interval of at least the silent interval (3.5 characters) between sending the next query.
■ (6) Normal response
 Returns the response according to the per-query formats described in "11.2 Explanation of
Modbus-RTU Function Codes".
■ (7) Abnormal response
 If there is a fault (excluding communication error) in the contents of the query, the inverter
returns an exceptional response without executing anything.
 To determine the error, check the function code of the response. The function code of the
exceptional response is the value added by 80h to the function code of the query.
 For error details, see section "11.2.9 Exceptional Responses".
Exceptional Response Field Configuration
Slave address
Function code
Exception code
CRC-16
■ (8) No response
 In the following cases, the inverter ignores the query and returns no response.
 A broadcast (a query with a slave address "0") is received.
 A communication error is detected during query reception.
 The slave address of the query does not match the inverter setting slave address.
 The time interval between the data composing the message is 3.5 characters or less.
 The query data length is invalid.
 The frame reception interval exceeds 1.5 characters.
 The error check code of the query does not match (CRC error).
 A group-wide broadcast (a query with a slave address between 250 and 254) is received.
 In the external control equipment, provide a timer to monitor the response message from the
inverter. If no response message is returned within a specific time, provide retransmission
processing or error processing, such as sending the same query again.
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Hitachi WJ C1 Series Specifications

General

Brand	Hitachi
Model	WJ C1 Series
Category	Inverter
Language	English