ALPHA-VISION® content: Softplc7 Command Interface

Softplc7 Command Interface

SUMMARY

CONTENTS

1. Introduction
2. Processing
3. Simulation Commands
4. API for the Interface
5. SoftPLC7.ini

The SoftPLC7 offers an Interface to communicate between an Instructor Station and several SoftPLC7 Instances of an Emulator Platform. Thus provides the opportunity to simulate the emulation. The standard functionalities like start, continue and time information are supported. In addition snapshots can be saved and restored.

Prior of using the interface a Plugin-Function of the SoftPLC7 must be activated to handle and control the communication; activation is done by an entry in the SoftPLC7.ini file:

[Plugin-Function] 
Func1=S7Sync,S7SyncControl
                  

While initializing the Plugin a named Shared-Memory-Area as well as a named event for use by the communication is created. The sequence control of the SoftPLC7 will be enlarged in the following way:

• The SoftPLC7 is in a wait state until the named event is signalized.
• By signalizing (SetEvent()) a new Time-Slice in the SoftPLC7 is triggered.
• A simulation command is read out of the Shared-Memory-Area and executed if applicable. Replies are written to the same Shared-Memory-Area.
• Any OBs lined for that Time-Slice are executed.
• A further named event signalizes the end of the Time-Slice.

To implement these activities a further process, a Control-Instance that deals with communication via the Shared-Memory and the Event-Setting on any SoftPLC7-Instance, is necessary.

To differ between the communication partners any instance got a number. The SoftPLC-Instances use the numbers 2,3,4 etc; 1 is reserved for the Control-Instance.

Naming for the entries in the SoftPLC7.ini file:

[IPC-SYNC]
INSTNR=2
SNAPBUFSIZE=2
SHMNAME=Name_Shared-Memory
OWNSEM=Name_First_Event
NEXTSEM=Name_Second_Event
                  

For Interprocess-Comminication the Shared-Memory is used in both directions, it complies with the following structure SYNC_STRUCT. Any elementary data types are stored in the Intel format ‘little endian’.

typedef struct
{
       long lVersion;     /* not used yet */
       char achBuffer[1]; /* data for Parameter or Snapshots */
} SNAP_BUF;

typedef struct
{
       short sFreezed;    /* not used yet */
       short sCommand;    /* contains command to be executed */
       short sStatusLo;   /* contains additional status information*/
       short sStatusHi;   /* contains status */
       long lSnpDataSize; /* length of the structure SNAP_BUF incl. achBuffer[...] */
       SNAP_BUF snpbuf;
} SYNC_STRUCT;

After the signalizing of the first event is realized by the SoftPLC7 the command is read and executed. It is defined by the value of sCommand and may take the values listed below. After a command is executed the sStatusHi is set to ‘RD’ for “ready” or ‘ER’ for “error” in case an error occurred. sStatusLo is set ‘0’ and sCommand to ‘NO’.

For convenient use of the interface the following functions are available in a library:

This function returns a handle to a Shared-Memory-Area; it is used for the communication between the Control-Instance and the SoftPLC7. If the area is not defined by the SoftPLC7 yet it will be created by that function call.

The Control-Instance creates an event for any SoftPLC-Instance; that event is signalized after any Time-Slice by the SoftPLC7. The event a SoftPLC7 is - prior a Time-Slice - waiting for, is created by the SoftPLC7 itself; it is referenced to via a handle by the Function-Call.

The function waits a maximum of dwMilliseconds for an event and resets it if no timeout occurred.

The function signalizes an event.

INI-FILES

Section [Plugin-Functions]

Func1=S7Sync,S7SyncControl
				

Section [IPC-SYNC]