Danfoss VLT AutomationDrive FC 300 Design Manual page 170

9. RS-485 Installation and Set-up
9.4.8. Parameter Number (PNU)
Bits no. 0-11 transfer parameter numbers. The function of the relevant parameter is defined in the parameter description in the Programming Guide.
9.4.9. Index (IND)
The index is used together with the parameter number to read/write-access parameters with an index, e.g. par. 15-30
2 bytes, a low byte and a high byte.
NB!
Only the low byte is used as an index.
9.4.10. Parameter Value (PWE)
The parameter value block consists of 2 words (4 bytes), and the value depends on the defined command (AK). The master prompts for a parameter
value when the PWE block contains no value. To change a parameter value (write), write the new value in the PWE block and send from the master to
the slave.
When a slave responds to a parameter request (read command), the present parameter value in the PWE block is transferred and returned to the master.
If a parameter contains not a numerical value but several data options, e.g. par. 0-01 Language where [0] corresponds to English, and [4] corresponds
to Danish, select the data value by entering the value in the PWE block. See Example - Selecting a data value. Serial communication is only capable of
reading parameters containing data type 9 (text string).
9
Parameters 15-40 to 15-53 contain data type 9.
For example, read the unit size and mains voltage range in par. 15-40
variable, and the texts are of different lengths. The telegram length is defined in the second byte of the telegram, LGE. When using text transfer the
index character indicates whether it is a read or a write command.
To read a text via the PWE block, set the parameter command (AK) to 'F' Hex. The index character high-byte must be "4".
Some parameters contain text that can be written to via the serial bus. To write a text via the PWE block, set the parameter command (AK) to 'F' Hex.
The index characters high-byte must be "5".
170
FC Type
. When a text string is transferred (read), the length of the telegram is
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FC 300 Design Guide
Error Code
. The index consists of