Danfoss FC 300 Design Manual page 280

FC 300 Design Guide
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).
Parameters 15-40 to 15-53 contain data type 9.
For example, read the unit size and mains voltage range in par. 15-40 FC Type. When a text string is
transferred (read), the length of the telegram is 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".
Data Types Supported by FC 300
Unsigned means that there is no operational sign
in the telegram.
Conversion
The various attributes of each parameter are dis-
played in the section Factory Settings. Parameter
values are transferred as whole numbers only.
Conversion factors are therefore used to transfer
decimals.
Par. 4-12 Motor Speed, Low Limit has a conver-
sion factor of 0.1.
To preset the minimum frequency to 10 Hz, trans-
fer the value 100. A conversion factor of 0.1
280
RS-485 Installation and Set-up
means that the value transferred is multiplied by
0.1. The value 100 is thus perceived as 10.0.
MG.33.B7.02 - VLT is a registered Danfoss trademark
Data types Description
3 Integer 16
4 Integer 32
5 Unsigned 8
6 Unsigned 16
7 Unsigned 32
9 Text string
10 Byte string
13 Time difference
33 Reserved
35 Bit sequence