GN-9289 User Manual
Page 44 of (70)
G-series GN-9289 Modbus TCP_UDP Rev. 1.01.docx
8.2.11. Error Response
In an exception response, the server sets the MSB of the function code to 1. This makes the function code
value in an exception response exactly 80 hexadecimal higher than the value would be for a normal
response.
Exception Response Example
Exception Codes
Exception
Code
Name
Description
01
Illegal Function
The function code received in the query is not an allowable
action for the server (or slave).
02
Illegal Data Address
The data address received in the query is not an allowable
address for the server (or slave).
03
Illegal Data Value
A value contained in the query data field is not an allowable
value for server (or slave).
04
Slave Device Failure
An unrecoverable error occurred while the server (or slave)
was attempting to perform the requested action.
05
Acknowledge
The server (or slave) has accepted the request and is
processing it, but a long duration of time will be required to do
so.
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
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
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.
- GN-9289 response exception code 01, 02, 03, 04 and 06.
Field name
Example
Function Code
0x81
Exception Code
0x02
