Rockwell Automation Publication 2071-RM001B-EN-P - April 2013
Modbus protocol uses the following exception codes from the Modbus
Exception Code Name
The function code received in the query is not an allowable action for the
The data address received in the query is not an allowable address for the
(1) Exception code 0x03 indicates an Illegal Data Value. It means the length of data string is incorrect. Exception code 14(0x0E) indicates
an Illegal Data Range. It means that data range exceeds the limit of the minimum or maximum value.
Illegal Data Value The length of query data field is not valid for the slave.
Slave Device Busy The slave is engaged in processing Run command. The master should
retransmit the message later when the slave is free.
Illegal CRC Value
The CRC value received in the query is wrong value.
The byte length of the Query Reception frame is out of the limit.
(2) Exception code 0x0D is generated if the master accesses a 32-bit data address with function code 06 or either the high or low
address of 32-bit data with function code 10.
The data sequence received in the query is not an allowable write command
for the slave.
Illegal Data Range The value of query data field is not valid for the slave.
(3) Exception code 15(0x0F) indicates an Illegal Command was issued. It occurs when a received Run control cannot be executed at the
The slave is in Run control and received an invalid command.
(4) Exception code 16(0x10) is an Illegal Control. It occurs when the Network Control Mode is not set, but the drive requests a Run
Control command or an I/O Control command through the network.
The slave is not in the Network mode, but received a network control
Servo On Write
Attempted to write to parameters that are inaccessible when the servo
drive is enabled.
Servo Error Fail
When the slave is Servo Error condition, and receives a Servo ON command
Drive Type Fail
When drive type of the slave is Indexing, slave receives run command 02,