Intelligent Technologies Modbus to QCPort Adapter Manual
January 2006
MN05002002E (C)
For more information visit
www.eatonelectrical.com
Page 60
Table 59-Modbus Exception Codes
Code Name
Meaning
01 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 unconfigured and is being asked to return register
values.
02 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.
03 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 specifically does NOT mean that a data item submitted
for storage in a register has a value outside the expectation of the
application program, since the MODBUS protocol is unaware of
the significance of any particular value of any particular register.
04 Slave
device
failure
An unrecoverable error occurred while the server (or slave) was
attempting to perform the requested action.
05 Acknowledge
Specialized use in conjunction with programming commands.
The server (or slave) has accepted the request and is processing
it, but a long duration of time will be required to do so. This
response is returned to prevent a timeout error from occurring in
the client (or master). The client (or master) can next issue a Poll
Program Complete message to determine if processing is
completed.
06 Slave
device
busy
Specialized use in conjunction with programming commands.
The server (or slave) is engaged in processing a long–duration
program command. The client (or master) should retransmit the
message later when the server (or slave) is free.
08 Memory
parity
error
Specialized use in conjunction with function codes 20 and 21 and
reference type 6, to indicate that the extended file area failed to
pass a consistency check.
The server (or slave) attempted to read record file, but detected a
parity error in the memory. The client (or master) can retry the
request, but service may be required on the server (or slave)
device.
0a Modbus
adapter path
unavailable
Specialized use in conjunction with Modbus adapter, indicates that
the Modbus adapter was unable to allocate an internal
communication path from the input port to the output port for
processing the request. Usually means that the Modbus adapter is
misconfigured or overloaded.
0b Modbus
adapter target
device failed
to respond
Specialized use in conjunction with Modbus adapter, indicates that
no response was obtained from the target device. Usually means
that the device is not present on the network.
