Danfoss VLT HVAC Drive FC 100 Series, Руководство по конструкции

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7.4.3 Message Length (LGE)
The message length is the number of data bytes plus the address byte ADR and the data control byte BCC.
The length of messages with 4 data bytes is LGE = 4 + 1 + 1 = 6 bytes
The length of messages with 12 data bytes is LGE = 12 + 1 + 1 = 14 bytes
The length of messages containing texts is 10 1) +n bytes
1)
The 10 represents the fixed characters, while the “n’” is variable (depending on the length of the text).
7.4.4 Adjustable Frequency Drive Address (ADR)
Two different address formats are used.
The address range of the Adjustable frequency drive is either 1-31 or 1-126.
1. Address format 1-31:
Bit 7 = 0 (address format 1-31 active)
Bit 6 is not used
Bit 5 = 1: Broadcast, address bits (0-4) are not used
Bit 5 = 0: No Broadcast
Bit 0-4 = Adjustable frequency drive address 1-31
2. Address format 1-126:
Bit 7 = 1 (address format 1-126 active)
Bit 0-6 = Adjustable frequency drive address 1-126
Bit 0-6 = 0 Broadcast
The slave returns the address byte unchanged to the master in the response message.
7.4.5 Data Control Byte (BCC)
The checksum is calculated as an XOR-function. Before the first byte in the message is received, the calculated checksum is
0.
7.4.6 The Data Field
The structure of data blocks depends on the type of message. There are three message types, and the type applies for both
control messages (master=>slave) and response messages (slave=>master).
The three types of message are:
Process block (PCD)
The PCD is made up of a data block of 4 bytes (two 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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