Prosoft-technology MVI69-MCM User Manual download pdf (Page 107)

MVI69-MCM ♦ CompactLogix or MicroLogix Platform Reference

Modbus Communication Module User Manual

ProSoft Technology, Inc. Page 107 of 167

March 22, 2011

5.2.3 Main Logic Loop

Upon completing the power up configuration process, the module enters an

infinite loop that performs the following functions:

5.2.4 Backplane Data Transfer

The MVI69-MCM module communicates directly over the CompactLogix or

MicroLogix backplane. Data is paged 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 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 2 to 10 milliseconds.

The data is paged between the processor and the module using input and output

image blocks. You can configure the size of the blocks using the Block Transfer

Size parameter in the configuration file. You can configure blocks of 60, 120, or

240 words of data depending on the number of words allowed for your own

application.

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 may be set to 62, 122, or 242 words depending on

the block transfer size parameter set in the configuration file.

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 may be set to 61, 121, or 241

words depending on the block transfer size parameter set in the configuration

file.

1 2 ... 102 103 104 105 106 107 108 109 110 111 112 ... 166 167

No comments

Prosoft-technology MVI69-MCM User Manual Page 107