Exception Handlng - Siemens SITRANS F Operating Instructions Manual

Address
Function code
Byte Count
Slave ID
Run Indicator
Product Code
Transmitter Code No
Capability bits
Manufacturer name
Product name
Product major rev
Product minor rev
MODBUS module name
MODBUS module No
MODBUS module major rev
MODBUS module minor rev
CRC LO
CRC HI
6.7

Exception handlng

There is a defined set of exception codes to be returned by slaves in the event of problems.
All exceptions are signalled in the response from the slave by adding 80hex to the function
code of the request and following this byte by an exception code.
Table 6- 16 Exception codes
Exception code Exception text
(dec)
01 Illegal function
02 Illegal data address
03 Illegal data value
04 Slave device failure
06 BUSY-acknowledge
Modbus RTU RS485
Operating Instructions, 06/2010, A5E00753974-04
1
17
55
0x2A
0xFF
25 (0x19)
083H0222
0x01, 0xFF, 0x00
Siemens
MASS 6000
2
1
MODBUS RTU
0xFF
1
2
0x3f
0x98
Description
The function code received in the query is not an allowable action for
the slave
The data address received in the query is not an allowable address for
the slave.
A value contained in the query data field is not an allowable value for
the addressed location. This may indicate a fault in the structure of the
remainder of a complex request, such that the implied length is
incorrect.
The request is by some other reason not acceptable. It may e.g.
indicate that the data value to write is evaluated to be beyond limits.
The slave is processing a long-duration command. The master should
retransmit the message later when the slave is free.
Functions codes
6.7 Exception handlng
33