ProSoft Technology MVI56-BSAPS - Manual (Page 38)

MVI56-BSAPS ♦ ControlLogix Platform Ladder Logic
Bristol Babcock Serial Slave Module
Page 38 of 83 ProSoft Technology, Inc.
September 22, 2008
3.1.1 Backplane Control Object
This data object stores the variables required for the data transfer between the
processor and the MVI56-BSAPS module. The structure of the object is shown in
the following example:
3.1.2 User Data Objects
These objects hold data to be transferred between the processor and the MVI56-
BSAPS module. The user data is the read and write data transferred between the
processor and the module as "pages" of data up to 200 words long.
The read data (ReadData) is an array containing values that are read from
module database. For ease of use, this array should be dimensioned as an even
increment of 200 words. This data is paged up to 200 words at a time from the
module to the processor. The ReadData task is responsible for placing the data
received into the proper position in the read data array. Use this data for status
and control in the ladder logic of the processor.
The write data (WriteData) is an array contain value that is written into the
module database. For ease of use, this array should be dimensioned as even
increments of 200 words. This data is paged up to 200 words at a time from the
processor to the module. The WriteData task is responsible for placing the write
data into the output image for transfer to the module. This data is passed from
the processor to the module for status and control information for use in other
nodes on the network.