ProSoft Technology MVI69-103M - Manual (Page 74)

MVI69-103M ♦ CompactLogix or MicroLogix Platform Reference
IEC 60870-5-103 Master Communication Module
Page 74 of 131 ProSoft Technology, Inc.
November 3, 2008
Main Logic Loop
Upon completing the power up configuration process, the module enters an
infinite loop that performs the following functions:
Backplane Data Transfer
The MVI69-103M module communicates directly over the CompactLogix or
MicroLogix backplane. Data travels between the module and the CompactLogix
or MicroLogix processor across the backplane using the module's input and
output images. The update frequency of the data is determined by the 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.
Data received by the master drivers is placed in the module's input image. This
data is processed by the ladder logic in the CompactLogix or MicroLogix
processor.
The processor inserts data in the module's output image to transfer to the
module. The module's program extracts the data and transmits the data out to
the master driver to the serial network. Additionally, the CompactLogix or
MicroLogix processor can send special control blocks to the module to instruct it
to perform a special task.