Return Code	Significance
0	all ok
1	IPC interface not initialized
2	wrong parameter passing
-1	no graphical interface initialized

The communication mode is reset after each IPC call (function dal_gfi_cal_ipc) to the default value NOWAIT.

The communication modes have the following meaning:

• NOWAIT (default): asynchronous - program execution is continued without waiting for a result.
• WAIT: synchronous - program execution is only continued after the IPC call has delivered a return code.
• STACK: all IPC calls are written to a stack and executed in sequence (default for DataView, Version 3.0)