Danfoss VLT AutomationDrive FC 301, Design Manual, Page: 181 / 200

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
RS-485 Installation and Set...
VLT
®
AutomationDrive FC 301/FC 302 Design Guide, 0.25-75 kW
MG33BF02 - Rev. 2013-12-20 179
12 12