Prosoft-technology MVI56E-LDM Manual de usuario descargar pdf (Pagina 60)

Understanding the MVI56-LDM API ControlLogix Platform ♦ "C" Programmable

Developer's Manual Linux Application Development Module

Page 54 of 264 ProSoft Technology, Inc.

March 12, 2014

Creates a handle allowing access to the tag database of the controller by

invoking OCXcip_CreateTagDbHandl. Options for accessing the database are set

using OCXcip_SetTagDbOptions.

A test is then made to ensure that the local copy of the database matches the

controller's copy of the tag database. This is done using the

OCXcip_TestTagDbVer routine which will return a database empty error on the first

invocation, causing the local database to be rebuilt with the OCXcip_BuildTagDb

routine.

The database contents are then printed to the console via

print_database_symbols. print_data_symbols calls OCXcip_GetSymbolInfo for

each symbol (i.e., Tag) in the controller. It prints the name, dimensions if its an

array, the element size, and the type of each tag. If the type is simple,

print_cip_data_type is called. If the type is a structure, print_structure_info is

called to print information about each element of the structure.

print_structure_info uses OCXcip_GetStructInfo to get information about a

structure and then prints the name, data type, number of members, and overall

size to the console. It then request info about each member using

OCXcip_GetStructMbrInfo and prints that information (name, array dimension,

offset in structure, element size, and data type) to the console. Again, a data

type may be simple (print_cip_data_type) or a structure which causes a

recursive invocation of the print_structure_info routine.

In the main program, print_tag_info is called on "index". This routine uses

OCXcip_GatTagDbTagInfo to get information about this tag and prints that info to

the console.

The main loop then calls print_controller_status to check for changes in

controller status. This routine uses OCXcip_GetDeviceIdStatus to check the fault

state, run mode, and key switch mode of the controller. If any of these states

change, the new state is printed to the console.

The main loop then uses OCXcip_AccessTagData to read the value of the tag

"LDM_Test". The value of this tag is then incremented and written back to the

controller using the OCXcip_AccessTagData routine.

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Prosoft-technology MVI56E-LDM Manual de usuario Pagina 60