ProSoft Technology MVI69-ADM - Manual (Page 30)

Understanding the MVI-ADM API MVI-ADM ♦ 'C' Programmable
Developer's Guide 'C' Programmable Application Development Module
Page 30 of 342 ProSoft Technology, Inc.
February 20, 2013
3.4 ADM Functional Blocks
3.4.1 Database
The database functions of the ADM API allow the creation of a database in
memory to store data to be accessed via the backplane interface and the
application ports. The database consists of word registers that can be accessed
as bits, bytes, words, longs, floats or doubles. Functions are provided for reading
and writing the data in the various data types. The database serves as a holding
area for exchanging data with the processor on the backplane, and with a foreign
device attached to the application port. Data transferred into the module from the
processor can be requested via the serial port. Conversely, data written into the
module database by the foreign device can be transferred to the processor over
the backplane.
3.4.2 Backplane Communications
MVI46 Backplane Data Transfer
The MVI46-ADM module communicates directly over the backplane. All data for
the module is contained in the module's M1 file. Data is moved between the
module and the SLC processor across the backplane using the module's M-files.
The SLC scan rate and the communication load on the module determine the
update frequency of the M-files. The COP instruction can be used to move data
between user data files and the module's M1 file.
The following illustration shows the data transfer method used to move data
between the SLC processor, the MVI46-ADM module and the foreign network.
All data transferred between the module and the processor over the backplane is
through the M0 and M1 files. Ladder logic must be written in the SLC processor
to interface the M-file data with data defined in the user-defined data files in the
SLC.