Rockwell Automation 20-COMM-K CANopen Adapter - Manual (Page 50)

5-8 Using I/O Messaging
20-COMM-K CANopen Adapter User Manual
Publication 20COMM-UM012B-EN-P
Using Datalinks A Datalink is a mechanism used by PowerFlex drives to transfer data to and
from the controller. Datalinks allow a drive parameter value to be read or
written without using an SDO explicit message. When enabled, each
Datalink occupies two 16-bit or 32-bit words in both the input and output
image. Use adapter Parameter 08 - [Datalink Size] to determine whether
the drive uses 16-bit or 32-bit words for Datalinks.
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 cannot 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. Thus, use Datalinks when you need
to change a value of a parameter frequently.
Using 16-Bit Datalinks to Read/Write 32-Bit Parameters
This subsection only pertains to PowerFlex 70 (SC or EC), PowerFlex 700
(SC), and PowerFlex 700H drives which use 16-bit Datalinks. To read or
write a 32-bit parameter using 16-bit Datalinks, typically both Datalinks of
a pair (A, B, C, D) are set to the same 32-bit parameter. For example, to read
Parameter 10 - [Elapsed Run Time] in a PowerFlex 70 drive, both Datalink
A1 Out and Datalink A2 Out are set to “10.” Datalink A1 Out will contain
the least significant word (LSW) and Datalink A2 Out will contain the most
significant word (MSW).
32-bit data is stored in binary as follows:
In this example, the Parameter 10 - [Elapsed Run Time] value of 6553.9 Hrs
is read as “6553.9” in Datalink A1 Out and Datalink A2 Out.
Conversion Example:
Parameter 010 - [Elapsed Run Time] = 6553.9 Hrs
MSW = 0001
hex
= 0001
binary
= 2 16 = 65536
LSW = 0003
hex
=3
Engineering Value = 65536 + 3 = 65539
Parameter 10 Displayed Value = 6553.9 Hrs
MSW 2
31
through 2
16
LSW 2 15 through 2 0
Datalink Word Parameter Data (Hex)
A1 Out LSW 10 0003
A2 Out MSW 10 0001