Specifications

71
Schneider Electric
The Modbus Protocol (continued)
Diagnostic of program commands: Function 14
This command is used to indicate the diagnostic associated with exception response
7 (no acknowledgement) received when a program command is executed (function
13). It provides the diagnostic of the last program command executed.
Command not authorised for broadcast.
Syntax:
b Query.
b Response.
The sub-function code returned is the sub-function code of the last program
command executed, with the most significant bit forced to 1 if an error was detected
during execution.
Example: 82 for a run query (sub-function 2). The type of error is coded as follows:
E52382E52383
Slave no. OE CRC 16
1 byte 1 byte 2 bytes
Slave no.
Function
code
Frame
length
Sub-function
code
CRC 16
1 byte 1 byte 1 byte 2 bytes1 byte
Type of error
1 byte
N° Name Type of command that could
cause this error
00 No error
01 Command unknown, not authorised or
poorly executed (CPU dialogue error, for
example).
Any command.
02 Invalid virtual address (exceeds maximum
authorised address field).
Read or write in memory.
03 Memory protected. The user is trying to
read or write a memory that is already
occupied by another coupler (mutual
exclusion principle).
Read or write in memory.
04 Read or write at addresses that do not
physically exist (outside the address field
of the slave under consideration).
Read or write in memory.
08 Invalid number of words. Read or write in memory.
09 Command not authorised. Slave running. Write in memory.
10 Command not authorised. Slave not
connected.
Run, stop, read or write.
Guide to Integration
Modbus / Jbus