Rockwell Automation 1336T ControlNet Frn1.02 Rev 1.5 - Manual (Page 76)

4–34 Using Unscheduled Messaging
Publication 1336 FORCE–5.18 ––March, 1999
The Link Parameter Read message reads the source parameter
number that is linked to the specified sink parameter.
PLC Block Transfer Instruction Data
PLC Message Write instruction length: 3 words
PLC Message Read instruction length: 4 words
Message Length
3
Header
Word 1 Header
Word 1
PLC Decimal Value
2304
Header
Word 2
Header
Word 3
Header
Word 2
Header
Word 3
PLC Decimal Value
2304 –– Message OK
Sink Parameter Link
-30464 –– Message Error
0
Parameter Number
Data
Word 4
Message Structure
Source Parameter
Number
PLC Request –– PLC Message Write
Drive Response –– PLC Message Read
Message Operation
The Link Parameter Read function specified in the PMW reads the
source parameter that is linked to the requested sink parameter,
defined in word 3 of the header message. The source parameter is
returned in word 4 of the PMR.
If an error has occurred, word 2 of the PMR returns a value of
-30464.
Example
In this example, the link associated with parameter 101 was
requested from the drive. The PMW header message word 4 defines
the sink parameter of the requested link with a value of 101. The
linked source parameter 330 is returned in word 4 of the PMR.
1 0
N7:0
2 3 4 5 6 7 8 9
N7:90
PLC MSG
Write File
PLC MSG
Read File
Data Format
101 0
101 330
3
0
2304
2304
Link Read
Link Parameter Read