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Cooper Bussmann 915U-2 Wireless Mesh I/O and Gateway User Manual
99
Rev Version 1.2.2
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D - MODBUS ErrOr CODES
The following are Modbus error response codes that the Master will generate and write to a general purpose analog
register (30501, 40501, and so on) in the event of a poll fail.
Dec Code
Hex Code
Name
Meaning
65281
FF01
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 might also indicate that the server (or slave) is in the wrong
state to process a request of this type.
65282
FF02
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, the PDU addresses the first register as 0, and the last one
as 99. If a request is submitted with a starting register address of 96
and a quantity of 4 registers, this request will successfully operate
on registers 96, 97, 98, 99. If a request is submitted with a starting
register address of 96 and a quantity of 5, this request will fail with
Exception Code 0x02 “Illegal Data Address.”
65283
FF03
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. For example, it may indicate that
the implied length is incorrect. It does not mean that a data item
submitted for storage in a register has a value outside the expectation
of the application program. The Modbus protocol is unaware of the
significance of any particular value of any particular register.
65384
FF04
Slave Device Failure
An unrecoverable error occurred while the server (or slave) was
attempting to perform the requested action.
65285
FF05
Acknowledge
Specialized use in conjunction with programming commands.
The server (or slave) has accepted the request and is processing it, but
significant time will be required to complete this task. This response
is returned to prevent a timeout error from occurring in the client (or
master).
65286
FF06
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.
65288
FF08
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.
65290
FF0A
Gateway Path
Unavailable
Specialized use in conjunction with gateways. Indicates that the
gateway was unable to allocate an internal communication path from
the input port to the output port for processing the request. Typically
indicates that the gateway is mis-configured or overloaded.
65291
FF0B
Gateway Device Failed
to Respond
Specialized use in conjunction with gateways. Indicates that no
response was obtained from the target device. Typically indicates that
the device is not present on the network.
65024
FE00
Invalid Response from
Slave
Command type or slave address did not match request (probably
another unit).
64512
FC00
Server Offline
Could not connect to the Modbus TCP server.
63488
F800
Invalid Local Memory
Address
Local address is invalid in the command. The memory location does
not exist or is not initialized.
65535
FFFF
No Response to the
Poll
There was no response to the poll message.
