Omron RX Series - Page 485

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8 Communications Functions
High-function General-purpose Inverter 3G3RX-V1 User’s Manual (I578-E1)
8-2 Modbus Method
8
<Abnormal Response>
Field Configuration
• If an error (except for a communications error) is found in the query content, the inverter will return an
exception response without performing any operation.
• For the cause of an error, check the function code for the response. The function code for an
exception response is the sum of the function code for the query and 80 hex.
• For the cause of an error, check the exceptional code.
Exception code
<No Response>
The inverter will ignore the query and send back no response if:
• It receives a broadcast query.
• It detects a communications error in receiving a query.
• The slave address specified in a query does not match the inverter’s slave address setting.
• The length of the time interval set for the inverter to receive the next data of the message after
receiving a message is less than 3.5 characters.
• The data length of a query is inappropriate.
• The length of the reception interval in a frame exceeds the 1.5 characters.
• The error check code specified in a query does not match (CRC error).
Note Provide a timer on the master side for monitoring the response and set it to resend the same query if no
response is received within the set time.
Slave address
Function code
Exception code
CRC-16
Code Description
01 hex An unsupported function is specified.
02 hex The specified address does not exist.
03 hex The specified data is in an unacceptable format.
21 hex Writing to a holding register is specified, but the data is out of the range allowed for the inverter.
22 hex
The inverter does not allow this function because:
• Inverter is in an operation busy state.
• Function attempts to change a register that cannot be changed during RUN.
• Function attempts to issue the Enter command during RUN (in an undervoltage state).
• Function attempts to write data to a register during trip (in an undervoltage state).
• Function attempts to write data to a read-only register (coil).