Frequency Converter Address (Adr); Data Control Byte (Bcc); The Data Field; The Pke Field - Danfoss VLT AutomationDrive FC 360 Design Manual

RS485 Installation and Set-...

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⇒follower) and response
telegrams (follower⇒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
follower)
•
Status word and present output frequency (from
follower to master)
STX LGE ADR PCD1
Illustration 5.5 Process Block
Parameter block
The parameter block is used to transfer parameters
between master and follower. The data block is made up
of 12 bytes (6 words) and also contains the process block.
STX LGE ADR PKE IND PWE
high
Illustration 5.6 Parameter Block
Text block
The text block is used to read or write texts via the data
block.
STX LGE ADR PKE IND Ch1 Ch2
Illustration 5.7 Text Block
MG06B402
Design Guide
PCD2 BCC
PWE PCD1 PCD2 BCC
low
Chn PCD1 PCD2 BCC
Danfoss A/S © 09/2014 All rights reserved.

5.4.7 The PKE Field

The PKE field contains 2 subfields:
•
Parameter command and response (AK)
•
Parameter number (PNU)
PKE IND
AK PNU
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
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
PWE PWE
high low
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