PN 305200901, Rev YT
Modbus Functions
As the Modbus protocol is designed for communication among Programmable
Logic Controllers (PLCs), not all Modbus function codes supported by a slave
PLC are applicable to the 3050 Analyzer. Only the following relevant function
codes are implemented:
In accordance with Modbus protocol specications, all address references in
Modbus messages are numbered relative to zero. For example, the rst hold-
ing register in a Modbus slave being referenced as 40001 would be addressed
as zero (‘’).
Code Description
03 Read multiple holding registers (4x references)
06 Write one holding register (4x references)
16 Write multiple holding registers (4x references)
17 Read slave ID and status information
Exception Code
The 3050 Analyzer Modbus protocol implementation supports these exception
codes:
Code Description
01 Illegal Function
02 Illegal Address
03 Illegal Value
Unsupported function requests from the Modbus master result in exception
code 01 being returned. Illegal address exception code is returned when the
requested address is outside the allowed range or writing to a read-only loca-
tion. When the values to be written to holding registers are outside the appro-
priate ranges, exception code 03 is returned.
6-4 | 3050-OLV Moisture Analyzer
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