7.3.6 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 telegrams (master=>slave) and
response telegrams (slave=>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
slave)
-
Status word and present output frequency (from
slave to master)
Illustration 7.7
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.
Illustration 7.8
Text block
The text block is used to read or write texts via the data
block.
Illustration 7.9
7.3.7 The PKE Field
The PKE field contains two sub-fields: Parameter command
and response AK, and Parameter number PNU:
Illustration 7.10
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