7.4.6 The Data Field
The structure of data blocks depends on the type of message. There are three message 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)
ADRLGESTX PCD1 PCD2 BCC
130BA269.10
Figure 7.5 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 INDADRLGESTX PCD1 PCD2 BCC
130BA271.10
PWE
high
PWE
low
Figure 7.6 Parameter Block
Text block
The text block is used to read or write texts via the data block.
PKE IND
130BA270.10
ADRLGESTX PCD1 PCD2 BCCCh1 Ch2 Chn
Figure 7.7 Text Block
RS-485 Installation and Set... Design Guide
90 Danfoss A/S © Rev. 2014-01-14 All rights reserved. MG18C522
77
To Next Page
Loading...
Need help?
General