Danfoss VLT HVAC Basic Drive FC 100 Series Design Manual page 68

RS-485 Installation and Set...
The 3 types of are:
Process block (PCD)
The PCD is made up of a data block of 4 bytes (2 words) and contains:
- Control word and reference value (from master to slave)
- Status word and present output frequency (from slave to master)
STX LGE ADR
Parameter block
The parameter block is used to transfer parameters between master and slave. The data block is made up of 12 bytes (6
words) and also contains the process block.
STX LGE ADR
Text block
The text block is used to read or write texts via the data block.
STX LGE ADR PKE
7.4.7 The PKE Field
The PKE field contains two subfields: Parameter command
and response (AK) and Parameter number (PNU):
PKE IND
AK PNU
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Bits no. 12-15 transfer parameter commands from master
to slave and return processed slave responses to the
master.
VLT HVAC Basic Drive Design Guide
PCD1
PWE
PKE IND
high
IND Ch1 Ch2
PWE PWE
high low
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PCD2
PWE
PCD1
low
Chn PCD1
Parameter commands master ⇒ slave
Bit no. Parameter command
15 14 13 12
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 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
BCC
PCD2 BCC
PCD2 BCC
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