Rockwell Automation 20-COMM-I Interbus Adapter - Manual (Page 54)

5-4 Using I/O Messaging
When enabled, the Logic Command/Status word is always word 0 in the
I/O image. The Logic Command is a 16-bit word of control produced by
the scanner and consumed by the adapter. The Logic Status is a 16-bit
word of status produced by the adapter and consumed by the scanner.
This manual contains the bit definitions for compatible products
available at the time of publication in
Appendix C , Logic Command/
Status Words . For other products, refer to their documentation.
When enabled, Reference/Feedback always begins at word 1 in the I/O
image. The Reference (16 bits or 32 bits) is produced by the controller
and consumed by the adapter. The Feedback (16 bits or 32 bits) is
produced by the adapter and consumed by the controller. The size of the
Reference/Feedback is determined by the product and displayed in
Parameter 03 - [Ref/Fdbk Size] in the adapter.
A Datalink is a mechanism used by PowerFlex drives to transfer data to
and from the controller. Datalinks allow a parameter value to be changed
without using an Explicit Message. When enabled, each Datalink
consumes either two 16-bit or 32-bit words in both the input and output
image depending on its size. The size of Datalinks (16-bit words or
32-bit words) is determined by the drive and displayed in Parameter 04
- [Datalink Size] in the adapter.
Rules for Using Datalinks
• Each set of Datalink parameters in a PowerFlex drive can be used by
only one adapter. If more than one adapter is connected to a single
drive, multiple adapters must not try to use the same Datalink.
• Parameter settings in the drive determine the data passed through the
Datalink mechanism. Refer to the documentation for your product.
• When you use a Datalink to change a value, the value is not written
to the Non-Volatile Storage (NVS). The value is stored in volatile
memory and lost when the drive loses power.
Using Logic Command/Status
Using Reference/Feedback
Size Valid Values In I/O Image Example
16-bit -32768 to 32767 Word 1 Figure 5.1
32-bit -2147483648 to 2147483647 Word 1 and Word 2 Figure 5.2
Using Datalinks
20COMM-UM007A-EN-P.book Page 4 Tuesday, January 22, 2002 10:52 AM