7.3.9 Index (IND)
The index is used with the parameter number to read/
write-access parameters with an index, e.g. 15-30 Alarm
Log: Error Code. The index consists of 2 bytes, a low byte
and a high byte.
Only the low byte is used as an index.
7.3.10 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 follower.
When a follower 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. parameter 0-01 Language where [0] is English, and [4]
is Danish, select the data value by entering the value in
the PWE block. Serial communication is only capable of
reading parameters containing data type 9 (text string).
15-40 FC Type to parameter 15-53 Power Card Serial Number
contain data type 9.
For example, read the unit size and mains voltage range in
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.
Illustration 7.9 Text via PWE Block
7.3.11 Supported Data Types
Unsigned means that there is no operational sign in the
telegram.
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
Table 7.7 Supported Data Types
7.3.12
Conversion
The various attributes of each parameter are displayed in
factory setting. Parameter values are transferred as whole
numbers only. Conversion factors are therefore used to
transfer decimals.
A conversion factor of 0.1 means that the value transferred
is multiplied by 0.1. The value 100 is therefore read as
10.0.
Examples:
0 s⇒conversion index 0
0.00 s⇒conversion index -2
0 ms⇒conversion index -3
0.00 ms⇒conversion index -5
RS485 Installation and Set-... Operating Instructions
MG90V302 Danfoss A/S © 09/2014 All rights reserved. 73
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