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10 Handling of the objects
10.1
Communication channel
The communication channel (PKW area) has the following structure:
Designation
PKE
PKW Bereich
IND PWE-high PWE-low
Inhalt
Parameter identification
High
Byte
Low
Byte
Index Parameter value
High
Byte
Low
Byte
High-Word
High
Byte
Index 0
Low-Word
Low Byte High
Byte
Low Byte
Byte No.
The data are transmitted in the Motorola format as, for example, supported by the
S7 PLC from Siemens. Thus, the high byte is on the lower byte and the low byte on the higher byte.
Note:
PKE
The index is always on the high byte of "Index“ (Byte No. 2), with the low byte always = 0.
Structure of the parameter identification (PKE):
High Byte Low Byte
15 14 13 11 10 9 8 7 6 5 4 3 2 1 0
PNU AK SPM
AK: Order or reply identification (value range 0 ..15)
SPM: Toggle bit for spontaneous result processing
PNU: Parameter number (value range 1 to 999)
• The order and reply identifications are stored in the AK area. If no parameter processing is to be done, the "no order" kind of function is to be set.
• With bit 11 (SPM), the readiness for spontaneous report processing can be switched on and off (0 = OFF, 1 = ON, in the present application, the spontaneous report processing is not support, so SPM is always 0).
•
The PNU area transmits the number of the parameter to be processed.
Parameter values (= data) of the type Integer/Unsigned Integer (16 Bit) and Long (32
Bit) can be written and read. The data type is specific in the order identification. In data set change-over capable parameters (array) the required data set is stated under
Index.
Note:
An Excel file, which can be requested, exists for the necessary information on the parameters with regard to the data type and data set change-over capacity.
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