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12.7.6 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)
ADR
LGE
STX
PCD1
PCD2
BCC
130BA269.10
Illustration 12.7 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.
PKE
IND
ADR
LGE
STX
PCD1
PCD2
BCC
130BA271.10
PWE
high
PWE
low
Illustration 12.8 Parameter Block
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
Illustration 12.9 Text Block
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AutomationDrive FC 301/FC 302 Design Guide, 0.25-75 kW
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