Serial Interface (Modbus RTU)
M-Max Series Adjustable Frequency Drive MN04020003E—October 2013 www.eaton.com 135
Structure of Exception Message
●
Address (of the master request)
●
Function code (of the master request): MSB is set to 1
(for example, with function code 06 = 1000 0110)
●
Data field contains the error code (is described in the
following table)
●
CRC
Error Code Description
Example:
Master request that contains a non-existent data address.
Master request: 01 06 0802 0001 EBAA (hex)
Slave response: 01 86 02 C3A1 (hex)
No Slave Response:
In the following cases, the frequency inverter ignores the
request and does not send a reply:
●
On receiving a broadcast request
●
If the request contains a transmission error
●
If the slave address in the request does not match that of
the frequency inverter
●
With an invalid data length,
(for example, reading of 12 registers) error message F08 is
triggered in the MMX
●
With a CRC or parity error
With a CRC error the value of system parameter S2.1 is
increased by 1 (xx = number of faulty messages)
●
If the time interval between the messages is less than
3.5. characters
The master must be programmed to repeat the request if it
does not receive a response within a specified time.
Exception Code Meaning Description
01 Illegal function This function is not supported
02 Illegal data address The address was not found
03 Illegal data value The data format is not permissible or is incorrect
04 Slave device error Occurrence of a non-regenerative error while the slave attempted to execute a slave response
06 Slave device busy The slave has received the master request error-free. However, it is engaged in processing a
lengthy command
hex Name
01 Slave address
06 Function code (here: Write a holding register)
0802 2050 (dec). The ID number of the written register is
2051 (dec) as the master PLC has an offset of +1
0001 Content (2 bytes) for register 42051:
0000 0000 0000 0001 (bin)
EBAA CRC
hex Name
01 Slave address
86 Function code (here: Write a holding register)
MSB was set to 1
02 Error code: Stated address not found.
C3A1 CRC
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