Prosoft-technology MVI69-DNPSNET Manual do Utilizador descarregar pdf (Página 69)

Reference MVI69-DNPSNET ♦ CompactLogix or MicroLogix Platform

Distributed Network Protocol Interface Module

ProSoft Technology, Inc. Page 69 of 119

November 3, 2008

Read Block

These blocks of data transfer information from the module to the CompactLogix

processor. The structure of the input image used to transfer this data is shown

below:

Offset Description

0 Read Block ID

1 Write Block ID

2 to n Read Data

where

n = 60, 120, or 240 depending on the Block Transfer Size parameter (refer to the configuration file).

The Read Block ID is an index value used to determine the location of where the

data will be placed in the CompactLogix or MicroLogix processor controller tag

array of module read data. The number of data words per transfer depends on

the configured Block Transfer Size parameter in the configuration file (possible

values are 60, 120, or 240).

The Write Block ID associated with the block requests data from the

CompactLogix or MicroLogix processor. Under normal, program operation, the

module sequentially sends read blocks and requests write blocks. For example, if

three read and two write blocks are used with the application, the sequence will

be as follows:

R1W1

R2W2 R3W1 R1W2 R2W1 R3W2 R1W1

This sequence will continue until interrupted by other write block numbers sent by

the controller or by a command request from a node on the DNP network or

operator control through the module's Configuration/Debug port.

The following example shows a typical backplane communication application.

Note: This example for reference only

Assume that the backplane parameters are configured as follows:

Read Register Start: 0

Read Register Count: 480

Write Register Start: 480

Write Register Count: 480

The backplane communication would be configured as follows:

1 2 ... 64 65 66 67 68 69 70 71 72 73 74 ... 118 119

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Prosoft-technology MVI69-DNPSNET Manual do Utilizador Página 69