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Overview of the DP Base Interface

DP Base Programming Interface for CP 5613/CP 5614

C79000-G8976-C108-01

3.9.3 Typical Sequences with Semaphores on the slave Module

Definition

The polling mode described in Section 3.7.3 can also be replaced by operation with

semaphores. The initialization of this mode, the elements of continuous operation

and canceling the mode are described below.

Initializing the Semaphore

Before it is used, the semaphore must be created as follows:

Step Action Meaning

1 Initialize a semaphore for

asynchronous jobs

(function

DP_init_sema_object)

The DP Base Lib provides a

semaphore for all asynchronous jobs

(type DP_OBJECT_TYPE_ASYNC).

Using Semaphores for the Slave Module

Step Action Meaning

1 Wait for the semaphore

(for example,

WaitForMultipleObjects)

The user program or the thread waits

until an event occurs.

"WaitForMultipleObjects" is a Windows

32-bit API function.

2 DPS_get_ind Fetch arrived indications

3a If DPS_CHK_PRM:

DPS_set_resp

If a new parameter assignment has

arrived:

Check user parameter data and

acknowledge positively or negatively

3b If DPS_CHK_CFG:

DPS_set_resp

If a new configuration has arrived:

Check configuration data and

acknowledge positively or negatively

4 Go to Step 1.

Note

After positive confirmation of configuration data, the input data in the process

ima

e table of the slave module must be written at least once

(

initialization

)

, before

the slave module can change to data exchange.

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