ProSoft Technology MVI56E-DNPNET - Manual (Page 81)

MVI56E-DNPNET ♦ ControlLogix Platform Contents
DNPNET Ethernet Client/Server Communication Module User Manual
ProSoft Technology, Inc. Page 81 of 140
February 13, 2015
Main Logic Loop
Upon completing the power up configuration process, the module enters an infinite loop
performing the following functions:
Backplane Data Transfer
The MVI56E-DNPNET module communicates directly over the ControlLogix backplane.
Data is paged between the module and the ControlLogix processor across the backplane
using the module's input and output images. The update frequency of the images is
determined by the scheduled scan rate defined by the user for the module and the
communication load on the module. Typical updates are in the range of 1 to 10 milliseconds
per block of information.
This bi-directional transference of data is accomplished by the module filling in data in the
module's input image to send to the processor. Data in the input image is placed in the
Controller Tags in the processor by the ladder logic. The input image for the module is set to
250 words. This large data area permits fast throughput of data between the module and the
processor.
The processor inserts data to the module's output image to transfer to the module. The
module's program extracts the data and places it in the module's internal database. The
output image for the module is set to 248 words. This large data area permits fast
throughput of data from the processor to the module.