Siemens SITRANS F Modbus RTU RS 485 - Page 34

If any doubts about the address that failed, "Last Coil/HoldReg ErrorAddr" can be read. This will
return the faulty address.
MODBUS reg‐
ister
MODBUS ad‐
dress
No. of
bytes
Data type Description Read/
write
4:00681 680 2 Word Last Coil ErrorAddr (MODBUS cmd: 1 or 5) R
4:00682 681 2 Word Last Coil ErrorNo (127 = No error) R
4:00683 682 2 Word Last HoldReg ErrorAddr (MODBUS cmd: 3 or 16) R
4:00684 683 2 Word Last HoldReg ErrorNo (127 = No error) R
Reading "Last Coil/HoldReg ErrorNo" will return a detailed error reason. A list of error numbers
can be seen below.
Error Number
(Dec)
Error Number
(Hex)
Error name Reason
3 3 Write access denied This parameter is in a state where it is not writ‐
able
4 4 Max. limit The value was greater than the allowed maxi‐
mum value
5 5 Min. limit The value was less than the allowed minimum
value
127 7F No error No problem
Functions codes
6.7 Exception handlng
Modbus RTU RS 485
34 Operating Instructions, 03/2021, A5E00753974-AB