How To Access Parameters - Danfoss FC 300 Design Manual

11 RS-485 Installation and Set-up

11.9 How to Access Parameters

11.9.1 Parameter Handling
The PNU (Parameter Number) is translated from the register address contained in the Modbus read or write message. The parameter number is translated
to Modbus as (10 x parameter number) DECIMAL.
11.9.2 Storage of Data
The Coil 65 decimal determines whether data written to the adjustable frequency drive is stored in EEPROM and RAM (coil 65 = 1), or only in RAM (coil
65 = 0).
11.9.3 IND
The array index is set in Holding Register 9 and used when accessing array parameters.
11.9.4 Text Blocks
Parameters stored as text strings are accessed in the same way as the other parameters. The maximum text block size is 20 characters. If a read request
for a parameter is for more characters than the parameter stores, the response is truncated. If the read request for a parameter is fewer characters than
the parameter stores, the response is space-filled.
11.9.5 Conversion Factor
The different attributes for each parameter can be seen in the section on factory settings. Since a parameter value can only be transferred as a whole
number, a conversion factor must be used to transfer decimals. Please refer to the
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11.9.6 Parameter Values
Standard Data Types
Standard data types are int16, int32, uint8, uint16 and uint32. They are stored as 4x registers (40001–4FFFF). The parameters are read using function
03HEX "Read Holding Registers." Parameters are written using the function 6HEX "Preset Single Register" for 1 register (16 bits), and the function 10HEX
"Preset Multiple Registers" for 2 registers (32 bits). Readable sizes range from 1 register (16 bits) up to 10 registers (20 characters).
Non standard Data Types
Non standard data types are text strings stored as 4x registers (40001–4FFFF). The parameters are read using function 03HEX "Read Holding Registers"
and written using function 10HEX "Preset Multiple Registers." Readable sizes range from 1 register (2 characters) up to 10 registers (20 characters).
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Parameters section
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FC 300 Design Guide
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