Danfoss VLT Midi Drive FC 280, Руководство по конструкции

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5.4.4 Frequency Converter Address (ADR)
Address format 1–126
•
Bit 7 = 1 (address format 1–126 active).
•
Bit 0–6 = frequency converter address 1–126.
•
Bit 0–6 = 0 broadcast.
The slave returns the address byte unchanged to the
master in the response telegram.
5.4.5 Data Control Byte (BCC)
The checksum is calculated as an XOR-function. Before the
first byte in the telegram is received, the calculated
checksum is 0.
5.4.6 The Data Field
The structure of data blocks depends on the type of
telegram. There are 3 telegram types, and the type applies
for both control telegrams (master
⇒
slave) and response
telegrams (slave
⇒
master).
The 3 types of telegram 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)
ADR LGE STX PCD1 PCD2 BCC
130BA269.10
Illustration 5.5 Process Block
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.
PKE IND ADR LGE STX PCD1 PCD2 BCC
130BA271.10
PWE
high
PWE
low
Illustration 5.6 Parameter Block
Text block
The text block is used to read or write texts via the data
block.
PKE IND
130BA270.10
ADR LGE STX PCD1 PCD2 BCC Ch1 Ch2 Chn
Illustration 5.7 Text Block
5.4.7 The PKE Field
The PKE field contains 2 subfields:
•
Parameter command and response (AK)
•
Parameter number (PNU)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
130BB918.10
PKE IND PWE
high
PWE
low
AK PNU
Par
amet
er
commands and r
eplies
Par
amet
er
number
Illustration 5.8 PKE Field
Bits 12–15 transfer parameter commands from master to
slave and return processed slave responses to the master.
Parameter commands master
⇒
slave
Bit number 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.
Table 5.5 Parameter Commands
Response slave
⇒
master
Bit number 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.
Table 5.6 Response
If the command cannot be performed, the slave sends this
response
0111 Command cannot be performed and issues
the following fault report in Table 5.7 .
RS485 Installation and Set-... Design Guide
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