Error Response - Hitachi HX-RIO3 Series User Manual

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7.1.11 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
Field name
Function Code
Exception Code
Exception Codes
Field name Example
01 Illegal Function
02 Illegal Data Address
03 Illegal Data Value
04 Slave Device Failure
06 Slave Device Busy
01 Illegal Function
Example
0x81
0x02
Description
The function code received in the query is not an allowable action
for the server (or slave).
The data address received in the query is not an allowable address
for the server (or slave).
A value contained in the query data field is not an allowable value
for server (or slave).
An unrecoverable error occurred while the server (or slave) was
attempting to perform the requested action.
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.
The function code received in the query is not an allowable action
for the server (or slave).
HX-RIO3 Series