Siemens SITRANS F Modbus RTU RS 485 - Exception Handling

Address 1
Function code 17
Byte Count 55
Slave ID 0x2A
Run Indicator 0xFF
Product Code 25 (0x19)
Transmitter Code No 083H0222
Capability bits 0x01, 0xFF, 0x00
Manufacturer name Siemens
Product name MASS 6000
Product major rev 2
Product minor rev 1
MODBUS module name MODBUS RTU
MODBUS module No 0xFF
MODBUS module major rev 1
MODBUS module minor rev 2
CRC LO 0x3f
CRC HI 0x98
6.7 Exception handlng
There is a de󹪝ned 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
(dec)
Exception text Description
01 Illegal function The function code received in the query is not an allowable action for the
slave
02 Illegal data address The data address received in the query is not an allowable address for the
slave.
03 Illegal data value A value contained in the query data 󹪝eld is not an allowable value for the
addressed location. This may indicate a fault in the structure of the re‐
mainder of a complex request, such that the implied length is incorrect.
04 Slave device failure 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.
06 BUSY-acknowledge The slave is processing a long-duration command. The master should
retransmit the message later when the slave is free.
If an exception code 04 is received, further requests have to be done to narrow down the exact
problem.
Functions codes
6.7 Exception handlng
Modbus RTU RS 485
Operating Instructions, 03/2021, A5E00753974-AB 33