Danfoss VLT 2800 Design Manual page 111

Programming
If a parameter does not contains a numerical value, but
several data options, e.g. parameter 001 Language where
corresponds to [0] English, and corresponds to [3] Danish,
the data value is selected by entering the value in the PWE
block. See Example - Selecting a data value.
Via serial communication it is only possible to read
parameters that have data type 9 (text string). Parameters
621 - 635 Nameplate data is data type 9. For example, in
parameter 621 Unit type it is possible to read the unit size
and mains voltage range.
When a text string is transferred (read), the length of the
telegram is variable, as the texts are of different lengths.
The telegram length is defined in the telegram's second
byte, known as LGE.
To be able to read a text via the PWE block, the parameter
command (AK) must be set to F hex.
The index character is used to indicate whether it is a read
or write command.
In a read command, the index must have the following
format:
Some frequency converters have parameters to which a
text may be written. To be able to write a text via the PWE
block, the parameter command (AK) must be set to F hex.
For a write command the text must have the following
format:
Data types supported by frequency transformer:
Data types Description
3 Integer 16
4 Integer 32
5 Unsigned 8
6 Unsigned 16
7 Unsigned 32
9 Text string
Unsigned means that there is no operational sign in the
telegram.
Example - Write a parameter value
Parameter 202 Output frequency high limit, f
changed to 100 Hz. The value must be recalled after a
mains failure, so it is written in EEPROM.
PKE=E0CA hex-Write for parameter 202 Output
frequency high limit, f
IND=0000 hex
PWE =0000 hex
HIGH
PWE =03E8 hex-Data value 1000,
LOW
corresponding to 100 Hz, see conversion.
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Design Guide
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The response from the slave to the master is:
Example - Selection of a data value
To select [20] kg/hour in parameter 416 Process units, recall
the value after a mains failure, so it is written in EEPROM.
PKE=E19F hex-Write for parameter 416 Process
units
IND=0000 hex
PWE =0000 hex
HIGH
PWE =0014 hex-Select data option [20] kg/hour
LOW
The response from the slave to the master is:
Example - Reading a parameter value
The value in parameter 207 Ramp up time 1 is required.
The master sends the following request:
PKE=10CF hex-read parameter 207 Ramp up time 1
IND=0000 hex
PWE =0000 hex
HIGH
PWE =0000 hex
LOW
If the value in parameter 207 Ramp-up time 1 is 10 s, the
response from the slave to the master is:
Conversion
See chapter 5.5 Parameter List with Factory Settings for
various attributes of each parameter. As a parameter value
can only be transferred as a whole number, a conversion
factor must be used to transfer decimals.
Example
Parameter 201 Output frequency, low limit f
conversion factor of 0.1. If the minimum frequency is
preset to 10 Hz, the value 100 must be transferred, as a
conversion factor of 0.1 means that the value transferred is
multiplied by 0.1. The value 100 is perceived as 10.0.
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