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
MAX
to be
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
MAX
IND=0000 hex
PWE
HIGH
=0000 hex
PWE
LOW
=03E8 hex-Data value 1000,
corresponding to 100 Hz, see conversion.
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
HIGH
=0000 hex
PWE
LOW
=0014 hex-Select data option
[20] kg/hour
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
HIGH
=0000 hex
PWE
LOW
=0000 hex
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
MIN
has a
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.
Programming
Design Guide
MG27E402
Danfoss A/S © Rev. May/2014 All rights reserved.
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