Danfoss VLT AutomationDrive FC 300 Design Manual page 168

9. RS-485 Installation and Set-up
Bit 0-4 = Frequency converter address 1-31
2. 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.
9.4.5. 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.
9.4.6. The Data Field
The structure of data blocks depends on the type of telegram. There are three telegram types, and the type applies for both control telegrams
(master=>slave) and response telegrams (slave=>master).
The three types of telegram are:
Process block (PCD):
The PCD is made up of a data block of four bytes (2 words) and contains:
- Control word and reference value (from master to slave)
- Status word and present output frequency (from slave to master).
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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.
Text block:
The text block is used to read or write texts via the data block.
9.4.7. The PKE Field
The PKE field contains two sub-fields: Parameter command and response AK, and Parameter number PNU:
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FC 300 Design Guide