5.2.13 Modbus Exception Codes
For a full explanation of the structure of an exception code response, please refer to the section
Modbus RTU Message Framing Structure, Function Field.
Modbus Exception Codes
Code
Name
Meaning
1
Illegal function
The function code received in the query is not an allowable action for the server (or slave). This may be
because the function code is only applicable to newer devices, and was not implemented in the unit selected.
It could also indicate that the server (or slave) is in the wrong state to process a request of this type, for
example because it is not configured and is being asked to return register values.
2
Illegal data address
The data address received in the query is not an allowable address for the server (or slave). More specifically,
the combination of reference number and transfer length is invalid. For a controller with 100 registers, a
request with offset 96 and length 4 would succeed, a request with offset 96 and length 5 will generate
exception 02.
3
Illegal data value
A value contained in the query data field is not an allowable value for server (or slave). This indicates a fault
in the structure of the remainder of a complex request, such as that the implied length is incorrect. It spe-
cifically does NOT mean that a data item submitted for storage in a register has a value outside the ex-
pectation of the application program, since the Modbus protocol is unaware of the significance of any
particular value of any particular register.
4
Slave device failure
An unrecoverable error occurred while the server (or slave) was attempting to perform the requested action.
5.3 Control Profile
The frequency converter can be controlled according to the GE Drive protocol. Select the desired control profile in par. O-10
Control Word Profile
. The choice of
profile affects the control and status word only.
The
GE Drive control profile
sections provide a detailed description of control and status data.
Modbus TCP
27
5
