GE AF-650 GP Design Manual page 185

AF-650 GP Design Guide
10.4.4 Frequency Converter Address (ADR)
Two different address formats are used.
The address range of the frequency converter 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 = 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.
10.4.5 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.
10.4.6 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 messages (master=>slave)
and response messages (slave=>master).
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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).
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.
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