Danfoss VLT FCD 311 Design Manual page 96

Data Character (byte)
The structure of data blocks depends on the type of
telegram. There are three types of telegram, and the
type of telegram applies for both control telegrams
(master ⇒slave) and response telegrams
(slave⇒master). The three types of telegram are:
- Parameter block, used to transfer parameters be-
tween master and slave. The data block is made
up of 12 bytes (6 words) and also contains the
process block.
- The process block is made up of a data block of
four bytes (2 words) and contains :
- Control word and reference value
- Status word and present output frequency
(from slave to master)
- Text block, which is used to read or write texts via
the data block.
Parameter commands and responses (AK).
Bits no. 12-15 are used to transfer parameter
commands from master to slave and the slave's pro-
cessed responses back to the master.
96
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VLT FCD Series
Parameter commands master⇒slave
Bit no.
15 14 13 12 Parameter command
0 0 0 0 No command
0 0 0 1 Read parameter value
0 0 1 0 Write parameter value in RAM
(word)
0 0 1 1 Write parameter value in RAM
(double word)
1 1 0 1 Write parameter value in RAM
and EEprom (double word)
1 1 1 0 Write parameter value in RAM
and EEprom (word)
1 1 1 1 Read/write text
Response slave⇒master
Bit no. Response
15 14 13 12
0 0 0 0 No response
0 0 0 1 Parameter value transferred
(word)
0 0 1 0 Parameter value transferred
(double word)
0 1 1 1 Command cannot be performed
1 1 1 1 Text transferred
If the command cannot be performed the slave
sends this response: 0111 Command cannot be
performed and gives the following fault report in the
parameter value (PWE):
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