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8.4.3 Telegram Length (LGE)
The telegram length is the number of data bytes plus the address byte ADR and the data control byte BCC.
The length of telegrams with 4 data bytes is LGE = 4 + 1 + 1 = 6 bytes
The length of telegrams with 12 data bytes is LGE = 12 + 1 + 1 = 14 bytes
The length of telegrams 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).
8.4.4 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.
8.4.5 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.
8.4.6 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 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
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
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
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