ProSoft Technology MVI69-ADM - Manual (Page 34)

Understanding the MVI-ADM API MVI-ADM ♦ 'C' Programmable
Developer's Guide 'C' Programmable Application Development Module
Page 34 of 342 ProSoft Technology, Inc.
February 20, 2013
The following illustration shows the data transfer method used to move data
between the ControlLogix processor, the MVI56-ADM module and the foreign
device.
All data transferred between the module and the processor over the backplane is
through the input and output images. Ladder logic must be written in the
ControlLogix processor to interface the input and output image data with data
defined in the Controller Tags.
All data used by the module is stored in its internal database. The following
illustration shows the layout of the database:
Module’s Internal Database Structure
5000 registers for user data 0
Register Data
4999
2000 words of configuration and
status data 5000
Status and Config
6999
Data contained in this database is paged through the input and output images by
coordination of the ControlLogix ladder logic and the MVI56-ADM module's
program. Up to 248 words of data can be transferred from the module to the
processor at a time. Up to 247 words of data can be transferred from the
processor to the module. Each image has a defined structure depending on the
data content and the function of the data transfer.