Allen-Bradley 20-COMM-M Modbus/TCP Adapter User Manual page 50

4-14 Using Modbus/TCP Function Codes
20-COMM-M Modbus/TCP Adapter User Manual
Publication 20COMM-UM014C-EN-P
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:
31 16
MSW 2 through 2
15 0
LSW 2 through 2
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.
Register Datalink Word
Address
10025 A1 Out LSW
10026
10027 A2 Out MSW
10028
Conversion Example:
Parameter 010 - [Elapsed Run Time] = 6553.9 Hrs
16
MSW = 0001 = 0001 = 2
hex binary
LSW = 0003 = 3
hex
Engineering Value = 65536 + 3 = 65539
Parameter 10 Displayed Value = 6553.9 Hrs
Regardless of the Datalink combination, Datalink x1 Out will always
contain the LSW and Datalink x2 Out will always contain the MSW. In the
following example, the PowerFlex 70 drive Parameter 242 - [Power Up
Marker] contains a value of 88.4541 Hrs.
Modbus Datalink Word
Address
10027 A2 Out MSW
10028
10029 B1 Out LSW
10030
Conversion Example:
Parameter 242 - [Power Up Marker] = 88.4541 hours
19
MSW = 000D = 1101 = 2
hex binary
LSW = 7F3D = 32573
hex
Engineering Value = 851968 + 32573 = 884541
Parameter 242 Displayed Value = 88.4541 Hrs
Parameter Data (Hex)
10 0003
0000
10 0001
0000
= 65536
Parameter Data (Hex)
242 000D
0000
242 7F3D
0000
18 16
+ 2 + 2 = 851968