ProSoft Technology MVI94-DNP - Manual (Page 80)

Reference MVI94-DNP ♦ Flex I/O
User Manual DNP 3.0 Server over Ethernet Communication Module
Page 80 of 131 ProSoft Technology, Inc.
December 17, 2010
5.4.2 Data Transfer
Data is transferred over the backplane using the module’s input and output
images. The module is configured with an eight-word input image and a seven-
word output image. The module and the Flex processor use these images to
page data and commands. The input image is set (written) by the module and is
read by the Flex processor. The output image is set (written) by the Flex
processor and read by the module. The following illustration shows this
relationship:
The module’s program is responsible for setting the block identification code
used to identify the data block written and the block identification code of the
block it wants to read from the processor. User definition of the database to use
with the module defines the blocks to be transferred between the module and the
processor.
Each read and write operation transfers a six-word data area. The processor
read operation contains a two-word header that defines the block identification
code of the read data and the block identification code of the write block
requested. These identification codes are in the range of 0 to 189, 300 to 349
and 400 to 449.