Danfoss VLT Series Design Manual page 131

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VLT HVAC Drive Design Guide
7.4.10. 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).
Parameters 15-40 to 15-53 contain data type 9.
For example, read the unit size and mains voltage range in par. 15-40
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".
7.4.11. Data Types Supported by VLT HVAC
Data types
3
4
5
6
7
9
10
13
33
35
Unsigned means that there is no operational
sign in the telegram.
Description
Integer 16
Integer 32
Unsigned 8
Unsigned 16
Unsigned 32
Text string
Byte string
Time difference
Reserved
Bit sequence
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MG.11.B2.02 - VLT is a registered Danfoss trademark
7. RS-485 Installation and Set-up
FC Type . When a text string
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