Prosoft-technology MVI69-MCM Bedienungsanleitung PDF herunterladen (Seite 71)

MVI69-MCM ♦ CompactLogix or MicroLogix Platform Ladder Logic

Modbus Communication Module User Manual

ProSoft Technology, Inc. Page 71 of 167

March 22, 2011

3.2 Module Data Object (MCM1ModuleDef)

All data related to the MVI69-MCM is stored in a user defined data type. An

instance of the data type is required before the module can be used. This is done

by declaring a variable of the data type in the Controller Tags Edit Tags dialog

box. The following table describes the structure of this object.

Name Data Type Description

BlockTransferSize INT

ReadData INT[480] Data read from module

WriteData INT[480] Data written to module

BP MCM1Backplane

ModuleStatus MCM1_STATUS

BlockRequest MCM1BlockRequest

CommandControl MCM1CommandControlPorts

EventCommand MCM1EventCommandPorts

SlavePollingControl MCM1SlavePollingControlPorts

SlaveStatus MCM1SlaveStatusPorts

MBCoil MCM1Coil_Array

This object contains objects that define the configuration, user data, status and

command control data related to the module.

This object reads and write data between the module and the processor. Values

entered determine the ladder logic and data size required in the application. The

ReadData and WriteData arrays must be sized to or larger than the count values

entered. The ladder logic must process the number of blocks of data to be

transferred. The number of blocks is computed as follows:

BlockCnt = INT(RegCnt/n) + if(MOD(RegCnt, n), 1,0)

Where n is the block transfer size, and equals 60, 120 or 240.

If the register count is evenly divisible by n, the number of blocks is easy to

compute and the ladder is much simpler to write. If the number is not evenly

divisible by n, special handling of the last block of data must be developed, as it

must transfer less than n words.

Important: It is recommended that the count values always be set to values evenly divisible by n.

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Prosoft-technology MVI69-MCM Bedienungsanleitung Seite 71