02.2004 Communication / USS
Siemens AG 6SE7087-6QX70 (Version AD)
SIMOVERT MASTERDRIVES Compendium Motion Control 8.1-11
8.1.2.2 PKW area
With the help of the PKW mechanism, the following tasks can be
performed via any serial interface with the USS protocol:
♦ Reading and writing parameters in the basic unit and, if available,
parameters on a technology board, e.g. T100
♦ Reading the description of a parameter
(applies to parameters of the basic unit and of technology boards)
♦ Reading of texts assigned to the indices of an indexed parameter.
(Applies to parameters of the basic unit and of the technology
modules.)
♦ Reading of texts assigned to the values of a parameter.
(Applies to parameters of the basic unit and of the technology
modules.)
The PKW area can be varied. Depending on the particular requirement,
3-word, 4-word or variable word lengths can be parameterized.
The following is an example of a structure when access (write/read) is
made to single-word (16 bit) parameter values:
1st word 2nd word 3rd word
PKE IND PWE1
Parameter ID Index Parameter value 1
The PKW area must be permanently set to 3 words at the master and
the slave. This setting is made during start-up and should not be altered
any more during bus operation.
The following is an example of a structure when access (write/read) is
made to double-word (32 bit) parameter values:
1
st
word 2
nd
word 3
rd
word 4
th
word
PKE IND PWE1 PWE2
High-Word Low Word
Parameter ID Index Parameter value (double word)
Parameterization to a fixed length of 4 words applies to telegrams from
the master to the slave and from the slave to the master. The setting
must be made both at the master and at the slave and can no longer be
altered during bus operation.
Settings in the PKW
area
PKW area
parameterized for 3
words
PKW area
parameterized to 4
words