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Description of the DP Functions, Data, and Error Codes

DP Base Programming Interface for CP 5613/CP 5614

112

C79000-G8976-C108-01

4.1.22 DP_init_sema_object

Purpose

This function initializes a semaphore for an event from the CP 5613/CP 5614 .

With Win32 API functions (WaitForMultipleObjects, WaitForSingleObject,

MsgWaitForMultipleObjects), a user program can wait at these semphores until an

event arrives.

Semaphores are synchronization objects that Win32 API interface also supports.

Using semaphores, it is possible to wait for the arrival of events in threads or

processes.

Note 1

If you want to use semaphores for CP 5614 master and slave modes at the same

time, initialize a master semaphore of the type DP_OBJECT_TYPE_ASYNC with

the user handle of the DP_open call and then initialize a further semaphore of the

type DP_OBJECT_TYPE_ASYNC but with the user handle of the DPS_open call.

Note 2

A semaphore initialized with DP_init_sema_object must only be deleted with the

DP_delete_sema_objet function. Never use Win32 API functions to delete such

semaphores.

Syntax

DPR_DWORD DP_init_sema_object(

DPR_DWORD user_handle, // in

DPR_DWORD sema_type, // in

DPR_DWORD *sema_handle, // out

DP_ERROR_T *error); // out

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