Rockwell Automation RECOMM-CNET ControlNet Communications Module - Manual (Page 55)

PLC-5C Applications 6-5
6.4 Using Reference/Feedback
The Reference (16 bits or 32 bits) is produced by the controller and
consumed by the module. The Feedback (16 bits or 32 bits) is
produced by the module and consumed by the controller. The size
of the Reference/Feedback is determined by the drive and displayed
in Ref/Fdbk Size (07) in the module.
6.5 Using Datalinks
A Datalink is a mechanism used by SP600 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 Datalink Size (08) in the module.
6.5.1 Rules for Using Datalinks
• Each set of Datalink parameters in an SP600 drive can be used
by only one module. If more than one module is connected to a
single drive, multiple modules 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 drive.
• 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.
Size Valid Values In I/O Image Example
16-bit -32768 to 32767 Word 1 Figure 6.1
32-bit -2147483648 to 2147483647 Word 2 and Word 3 Figure 6.2