Rockwell Automation 20-COMM-R Remote I/O Adapter - Manual (Page 45)

Using Discrete and Block Transfer I/O 4-9
20-COMM-R Remote I/O Adapter User Manual
Publication 20COMM-UM004D-EN-P
Datalink Scaling
PowerFlex 70/700/700H Drives and PowerFlex 700L Drives with 700 Control
Datalink scaling is not automatic and uses whole numbers (INTs or DINTs).
See the drive documentation to determine the unit resolution for the
associated parameter Datalink. For example, PowerFlex 700VC drive
parameter 3 - [Output Current] has a 0.1 unit resolution. Because Datalink
scaling uses whole numbers, the Output Current value is multiplied by 10 in
the adapter and then sent over the network. Suppose the actual Output
Current value is 35.5 amps. Reading the associated parameter Datalink
received by the controller, the value would be 355. By using ladder logic,
divide the value by 10 in the controller to get the correct scaling. See the
drive documentation to determine if the Datalink parameter is a 16-bit or
32-bit parameter.
PowerFlex 700S, PowerFlex 700L with 700S Control, PowerFlex 753/755, and
PowerFlex Digital DC Drives
Datalinks require scaling in the following way. Parameters are either 16-bit
or 32-bit integers or REALs. When the parameter is a 32-bit integer, the
data needs to be copied using a COP command to a DINT tag. (Because
PLC-5 and SLC 500 controllers do not support 32-bit integers, the data
must be separated into two 16-bit integers.) When the parameter is a REAL,
the data needs to be copied using a COP command to a REAL tag. See
subsequent sections in this chapter for ladder logic examples. See the drive
documentation to determine if the Datalink parameter is a 16-bit or 32-bit
integer parameter, or a REAL parameter.
Using 16-Bit Datalinks to Read/Write 32-Bit Parameters
This subsection only pertains to PowerFlex 70 (standard or enhanced
control), PowerFlex 700 (standard control), 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 (Parameter 310) and
Datalink A2 Out (Parameter 311) 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:
MSW 2 31 through 2 16
LSW 2 15 through 2 0