Rockwell Automation RECOMM-IBUS Interbus Communications Module - Manual (Page 53)

Using I/O Messaging 6-5
• 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.
6.5.2 32-Bit Parameters using 16-Bit Datalinks
To read (and/or write) a 32-bit parameter using 16-bit Datalinks,
typically both Datalinks (x1 and x2) are set to the 32-bit parameter.
For example, to read Elapsed MWh (9) in an SP600 drive, both
Datalink A1 and A2 are set to “9.” Datalink A1 will contain the least
significant word (LSW) and Datalink A2 the most significant word
(MSW). In this example, the parameter 9 value of 5.8 MWh is read
as a “58” in Datalink A1.
Regardless of the Datalink combination, x1 will always contain the
LSW and x2 will always contain the MSW. In the following
examples, Power Up Marker (242) contains a value of 88.4541
hours.
32-bit data is stored in binary as follows:
Datalink
Most/Least
Significant Word Parameter
Data
(decimal)
A1 LSW 9 58
A2 MSW 9 0
Datalink
Most/Least
Significant Word Parameter
Data
(decimal)
A1 LSW 242 32573
A2 - Not Used - 0 0
Datalink
Most/Least
Significant Word Parameter
Data
(decimal)
A1 - Not Used - 0 0
A2 MSW 242 13
Datalink
Most/Least
Significant Word Parameter
Data
(decimal)
A2 MSW 242 13
B1 LSW 242 32573
MSW 2 31 through 2 16
LSW 2 15 through 2 0