10.7.6 The Data Field
The structure of data blocks depends on the type of message. There are three types, and the type applies for both control
messages (master
⇒
follower) and response messages (follower
⇒
master).
The three types of message are:
Process block (PCD)
The PCD is made up of a data block of four bytes (two 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
Figure 10.6 PCD
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
Figure 10.7 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
Figure 10.8 Text Block
RS-485 Installation and Set...
Design Guide
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Summary of Contents for VLT AutomationDrive FC 300
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